changes to proration behavior

and returning more properties from the proration endpoint

src/Api/Billing/Controllers/PreviewInvoiceController.cs

@@ -70,6 +70,13 @@ public class PreviewInvoiceController(
             planType,
             billingAddress);
 
-        return Handle(result.Map(pair => new { pair.Tax, pair.Total, pair.Credit }));
+        return Handle(result.Map(proration => new
+        {
+            NewPlanProratedTotal = proration.NewPlanProratedAmount,
+            proration.Credit,
+            proration.Tax,
+            proration.Total,
+            proration.NewPlanProratedMonths
+        }));
     }
 }

src/Core/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommand.cs

@@ -2,6 +2,7 @@
 using Bit.Core.Billing.Constants;
 using Bit.Core.Billing.Enums;
 using Bit.Core.Billing.Payment.Models;
+using Bit.Core.Billing.Premium.Models;
 using Bit.Core.Billing.Pricing;
 using Bit.Core.Billing.Services;
 using Bit.Core.Entities;
@@ -22,8 +23,8 @@ public interface IPreviewPremiumUpgradeProrationCommand
     /// <param name="user">The user with an active Premium subscription.</param>
     /// <param name="targetPlanType">The target organization plan type.</param>
     /// <param name="billingAddress">The billing address for tax calculation.</param>
-    /// <returns>A tuple containing the tax amount, total cost, and proration credit from unused Premium time.</returns>
+    /// <returns>The proration details for the upgrade including costs, credits, tax, and time remaining.</returns>
-    Task<BillingCommandResult<(decimal Tax, decimal Total, decimal Credit)>> Run(
+    Task<BillingCommandResult<PremiumUpgradeProration>> Run(
         User user,
         PlanType targetPlanType,
         BillingAddress billingAddress);
@@ -36,19 +37,16 @@ public class PreviewPremiumUpgradeProrationCommand(
     : BaseBillingCommand<PreviewPremiumUpgradeProrationCommand>(logger),
       IPreviewPremiumUpgradeProrationCommand
 {
-    public Task<BillingCommandResult<(decimal Tax, decimal Total, decimal Credit)>> Run(
+    public Task<BillingCommandResult<PremiumUpgradeProration>> Run(
         User user,
         PlanType targetPlanType,
-        BillingAddress billingAddress) => HandleAsync<(decimal, decimal, decimal)>(async () =>
+        BillingAddress billingAddress) => HandleAsync<PremiumUpgradeProration>(async () =>
     {
         if (user is not { Premium: true, GatewaySubscriptionId: not null and not "" })
         {
             return new BadRequest("User does not have an active Premium subscription.");
         }
 
-        // Hardcode seats to 1 for upgrade flow
-        const int seats = 1;
-
         var currentSubscription = await stripeAdapter.GetSubscriptionAsync(
             user.GatewaySubscriptionId,
             new SubscriptionGetOptions { Expand = ["customer"] });
@@ -63,11 +61,7 @@ public class PreviewPremiumUpgradeProrationCommand(
 
         var usersPremiumPlan = premiumPlans.First(p => p.Seat.StripePriceId == passwordManagerItem.Price.Id);
         var targetPlan = await pricingClient.GetPlanOrThrow(targetPlanType);
-        var subscriptionItems = new List<InvoiceSubscriptionDetailsItemOptions>
+        var subscriptionItems = new List<InvoiceSubscriptionDetailsItemOptions>();
-        {
-            // Delete the user's specific password manager item
-            new() { Id = passwordManagerItem.Id, Deleted = true }
-        };
         var storageItem = currentSubscription.Items.Data.FirstOrDefault(i =>
             i.Price.Id == usersPremiumPlan.Storage.StripePriceId);
 
@@ -81,10 +75,12 @@ public class PreviewPremiumUpgradeProrationCommand(
             });
         }
 
+        // Hardcode seats to 1 for upgrade flow
         if (targetPlan.HasNonSeatBasedPasswordManagerPlan())
         {
             subscriptionItems.Add(new InvoiceSubscriptionDetailsItemOptions
             {
+                Id = passwordManagerItem.Id,
                 Price = targetPlan.PasswordManager.StripePlanId,
                 Quantity = 1
             });
@@ -93,8 +89,9 @@ public class PreviewPremiumUpgradeProrationCommand(
         {
             subscriptionItems.Add(new InvoiceSubscriptionDetailsItemOptions
             {
+                Id = passwordManagerItem.Id,
                 Price = targetPlan.PasswordManager.StripeSeatPlanId,
-                Quantity = seats
+                Quantity = 1
             });
         }
 
@@ -114,21 +111,26 @@ public class PreviewPremiumUpgradeProrationCommand(
             SubscriptionDetails = new InvoiceSubscriptionDetailsOptions
             {
                 Items = subscriptionItems,
-                ProrationBehavior = StripeConstants.ProrationBehavior.CreateProrations
+                ProrationBehavior = StripeConstants.ProrationBehavior.AlwaysInvoice
             }
         };
 
         var invoicePreview = await stripeAdapter.CreateInvoicePreviewAsync(options);
-        var amounts = GetAmounts(invoicePreview);
+        var proration = GetProration(invoicePreview, passwordManagerItem);
 
-        return amounts;
+        return proration;
     });
 
-    private static (decimal, decimal, decimal) GetAmounts(Invoice invoicePreview) => (
+    private static PremiumUpgradeProration GetProration(Invoice invoicePreview, SubscriptionItem passwordManagerItem) => new()
-        Convert.ToDecimal(invoicePreview.TotalTaxes.Sum(invoiceTotalTax => invoiceTotalTax.Amount)) / 100,
+    {
-        Convert.ToDecimal(invoicePreview.Total) / 100,
+        NewPlanProratedAmount = GetNewPlanProratedAmountFromInvoice(invoicePreview),
-        GetProrationCreditFromInvoice(invoicePreview));
+        Credit = GetProrationCreditFromInvoice(invoicePreview),
-
+        Tax = Convert.ToDecimal(invoicePreview.TotalTaxes.Sum(invoiceTotalTax => invoiceTotalTax.Amount)) / 100,
+        Total = Convert.ToDecimal(invoicePreview.Total) / 100,
+        // Use invoice periodEnd here instead of UtcNow so that testing with Stripe time clocks works correctly. And if there is no test clock,
+        // (like in production), the previewInvoice's periodEnd is the same as UtcNow anyway because of the proration behavior (always_invoice)
+        NewPlanProratedMonths = CalculateNewPlanProratedMonths(invoicePreview.PeriodEnd, passwordManagerItem.CurrentPeriodEnd)
+    };
 
     private static decimal GetProrationCreditFromInvoice(Invoice invoicePreview)
     {
@@ -139,4 +141,26 @@ public class PreviewPremiumUpgradeProrationCommand(
 
         return Convert.ToDecimal(prorationCredit) / 100;
     }
+
+    private static decimal GetNewPlanProratedAmountFromInvoice(Invoice invoicePreview)
+    {
+        // The target plan's prorated upgrade amount should be the only positive-valued line item
+        var proratedTotal = invoicePreview.Lines?.Data?
+            .Where(line => line.Amount > 0)
+            .Sum(line => line.Amount) ?? 0;
+
+        return Convert.ToDecimal(proratedTotal) / 100;
+    }
+
+    private static int CalculateNewPlanProratedMonths(DateTime invoicePeriodEnd, DateTime currentPeriodEnd)
+    {
+        var daysInProratedPeriod = (currentPeriodEnd - invoicePeriodEnd).TotalDays;
+
+        // Round to nearest month (30-day periods)
+        // 1-14 days = 1 month, 15-44 days = 1 month, 45-74 days = 2 months, etc.
+        // Minimum is always 1 month (never returns 0)
+        // Use MidpointRounding.AwayFromZero to round 0.5 up to 1
+        var months = (int)Math.Round(daysInProratedPeriod / 30, MidpointRounding.AwayFromZero);
+        return Math.Max(1, months);
+    }
 }

src/Core/Billing/Premium/Commands/UpgradePremiumToOrganizationCommand.cs

@@ -88,13 +88,6 @@ public class UpgradePremiumToOrganizationCommand(
         // Build the list of subscription item updates
         var subscriptionItemOptions = new List<SubscriptionItemOptions>();
 
-        // Delete the user's specific password manager item
-        subscriptionItemOptions.Add(new SubscriptionItemOptions
-        {
-            Id = passwordManagerItem.Id,
-            Deleted = true
-        });
-
         // Delete the storage item if it exists for this user's plan
         var storageItem = currentSubscription.Items.Data.FirstOrDefault(i =>
             i.Price.Id == usersPremiumPlan.Storage.StripePriceId);
@@ -116,6 +109,7 @@ public class UpgradePremiumToOrganizationCommand(
         {
             subscriptionItemOptions.Add(new SubscriptionItemOptions
             {
+                Id = passwordManagerItem.Id,
                 Price = targetPlan.PasswordManager.StripePlanId,
                 Quantity = 1
             });
@@ -124,6 +118,7 @@ public class UpgradePremiumToOrganizationCommand(
         {
             subscriptionItemOptions.Add(new SubscriptionItemOptions
             {
+                Id = passwordManagerItem.Id,
                 Price = targetPlan.PasswordManager.StripeSeatPlanId,
                 Quantity = seats
             });
@@ -136,7 +131,8 @@ public class UpgradePremiumToOrganizationCommand(
         var subscriptionUpdateOptions = new SubscriptionUpdateOptions
         {
             Items = subscriptionItemOptions,
-            ProrationBehavior = StripeConstants.ProrationBehavior.CreateProrations,
+            ProrationBehavior = StripeConstants.ProrationBehavior.AlwaysInvoice,
+            BillingCycleAnchor = SubscriptionBillingCycleAnchor.Unchanged,
             AutomaticTax = new SubscriptionAutomaticTaxOptions { Enabled = true },
             Metadata = new Dictionary<string, string>
             {
@@ -149,11 +145,6 @@ public class UpgradePremiumToOrganizationCommand(
             }
         };
 
-        if (targetPlan.TrialPeriodDays.HasValue)
-        {
-            subscriptionUpdateOptions.TrialEnd = DateTime.UtcNow.AddDays((double)targetPlan.TrialPeriodDays);
-        }
-
         // Create the Organization entity
         var organization = new Organization
         {
@@ -161,7 +152,7 @@ public class UpgradePremiumToOrganizationCommand(
             Name = organizationName,
             BillingEmail = user.Email,
             PlanType = targetPlan.Type,
-            Seats = (short)seats,
+            Seats = seats,
             MaxCollections = targetPlan.PasswordManager.MaxCollections,
             MaxStorageGb = targetPlan.PasswordManager.BaseStorageGb,
             UsePolicies = targetPlan.HasPolicies,

src/Core/Billing/Premium/Models/PremiumUpgradeProration.cs

@@ -0,0 +1,36 @@
+namespace Bit.Core.Billing.Premium.Models;
+
+/// <summary>
+/// Represents the proration details for upgrading a Premium user subscription to an Organization plan.
+/// </summary>
+public class PremiumUpgradeProration
+{
+    /// <summary>
+    /// The prorated cost for the new organization plan, calculated from now until the end of the current billing period.
+    /// This represents what the user will pay for the upgraded plan for the remainder of the period.
+    /// </summary>
+    public decimal NewPlanProratedAmount { get; set; }
+
+    /// <summary>
+    /// The credit amount for the unused portion of the current Premium subscription.
+    /// This credit is applied against the cost of the new organization plan.
+    /// </summary>
+    public decimal Credit { get; set; }
+
+    /// <summary>
+    /// The tax amount calculated for the upgrade transaction.
+    /// </summary>
+    public decimal Tax { get; set; }
+
+    /// <summary>
+    /// The total amount due for the upgrade after applying the credit and adding tax.
+    /// </summary>
+    public decimal Total { get; set; }
+
+    /// <summary>
+    /// The number of months the user will be charged for the new organization plan in the prorated billing period.
+    /// Calculated by rounding the days remaining in the current billing cycle to the nearest month.
+    /// Minimum value is 1 month (never returns 0).
+    /// </summary>
+    public int NewPlanProratedMonths { get; set; }
+}

test/Core.Test/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommandTests.cs

@@ -91,6 +91,8 @@ public class PreviewPremiumUpgradeProrationCommandTests
         var premiumPlans = new List<PremiumPlan> { premiumPlan };
 
         // Setup current Stripe subscription
+        var now = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        var currentPeriodEnd = now.AddMonths(6);
         var currentSubscription = new Subscription
         {
             Id = "sub_123",
@@ -106,7 +108,8 @@ public class PreviewPremiumUpgradeProrationCommandTests
                     new()
                     {
                         Id = "si_premium",
-                        Price = new Price { Id = "premium-annually" }
+                        Price = new Price { Id = "premium-annually" },
+                        CurrentPeriodEnd = currentPeriodEnd
                     }
                 }
             }
@@ -122,7 +125,15 @@ public class PreviewPremiumUpgradeProrationCommandTests
             TotalTaxes = new List<InvoiceTotalTax>
             {
                 new() { Amount = 500 } // $5.00
-            }
+            },
+            Lines = new StripeList<InvoiceLineItem>
+            {
+                Data = new List<InvoiceLineItem>
+                {
+                    new() { Amount = 5000 }  // $50.00 for new plan
+                }
+            },
+            PeriodEnd = now
         };
 
         // Configure mocks
@@ -140,10 +151,12 @@ public class PreviewPremiumUpgradeProrationCommandTests
 
         // Assert
         Assert.True(result.IsT0);
-        var (tax, total, credit) = result.AsT0;
+        var proration = result.AsT0;
-        Assert.Equal(5.00m, tax);
+        Assert.Equal(50.00m, proration.NewPlanProratedAmount);
-        Assert.Equal(50.00m, total);
+        Assert.Equal(0m, proration.Credit);
-        Assert.Equal(0m, credit);
+        Assert.Equal(5.00m, proration.Tax);
+        Assert.Equal(50.00m, proration.Total);
+        Assert.Equal(6, proration.NewPlanProratedMonths); // 6 months remaining
     }
 
     [Theory, BitAutoData]
@@ -174,6 +187,9 @@ public class PreviewPremiumUpgradeProrationCommandTests
         };
         var premiumPlans = new List<PremiumPlan> { premiumPlan };
 
+        // Use fixed time to avoid DateTime.UtcNow differences
+        var now = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        var currentPeriodEnd = now.AddDays(45); // 1.5 months ~ 2 months rounded
         var currentSubscription = new Subscription
         {
             Id = "sub_123",
@@ -182,7 +198,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             {
                 Data = new List<SubscriptionItem>
                 {
-                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" } }
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = currentPeriodEnd }
                 }
             }
         };
@@ -201,7 +217,8 @@ public class PreviewPremiumUpgradeProrationCommandTests
                     new() { Amount = -1000 },  // -$10.00 credit from unused Premium
                     new() { Amount = 5000 }    // $50.00 for new plan
                 }
-            }
+            },
+            PeriodEnd = now
         };
 
         _pricingClient.ListPremiumPlans().Returns(premiumPlans);
@@ -216,10 +233,12 @@ public class PreviewPremiumUpgradeProrationCommandTests
 
         // Assert
         Assert.True(result.IsT0);
-        var (tax, total, credit) = result.AsT0;
+        var proration = result.AsT0;
-        Assert.Equal(4.00m, tax);
+        Assert.Equal(50.00m, proration.NewPlanProratedAmount);
-        Assert.Equal(40.00m, total);
+        Assert.Equal(10.00m, proration.Credit);  // Proration credit
-        Assert.Equal(10.00m, credit);  // Proration credit
+        Assert.Equal(4.00m, proration.Tax);
+        Assert.Equal(40.00m, proration.Total);
+        Assert.Equal(2, proration.NewPlanProratedMonths); // 45 days rounds to 2 months
     }
 
     [Theory, BitAutoData]
@@ -258,7 +277,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             {
                 Data = new List<SubscriptionItem>
                 {
-                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" } }
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = DateTime.UtcNow.AddMonths(1) }
                 }
             }
         };
@@ -268,7 +287,9 @@ public class PreviewPremiumUpgradeProrationCommandTests
         var invoice = new Invoice
         {
             Total = 5000,
-            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } }
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } },
+            Lines = new StripeList<InvoiceLineItem> { Data = new List<InvoiceLineItem> { new() { Amount = 5000 } } },
+            PeriodEnd = DateTime.UtcNow
         };
 
         _pricingClient.ListPremiumPlans().Returns(premiumPlans);
@@ -281,10 +302,11 @@ public class PreviewPremiumUpgradeProrationCommandTests
         // Act
         await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
-        // Assert - Verify that the subscription item quantity is always 1
+        // Assert - Verify that the subscription item quantity is always 1 and has Id
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
             Arg.Is<InvoiceCreatePreviewOptions>(options =>
                 options.SubscriptionDetails.Items.Any(item =>
+                    item.Id == "si_premium" &&
                     item.Price == targetPlan.PasswordManager.StripeSeatPlanId &&
                     item.Quantity == 1)));
     }
@@ -325,8 +347,8 @@ public class PreviewPremiumUpgradeProrationCommandTests
             {
                 Data = new List<SubscriptionItem>
                 {
-                    new() { Id = "si_password_manager", Price = new Price { Id = "premium-annually" } },
+                    new() { Id = "si_password_manager", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = DateTime.UtcNow.AddMonths(1) },
-                    new() { Id = "si_storage", Price = new Price { Id = "storage-gb-annually" } }
+                    new() { Id = "si_storage", Price = new Price { Id = "storage-gb-annually" }, CurrentPeriodEnd = DateTime.UtcNow.AddMonths(1) }
                 }
             }
         };
@@ -336,7 +358,9 @@ public class PreviewPremiumUpgradeProrationCommandTests
         var invoice = new Invoice
         {
             Total = 5000,
-            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } }
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } },
+            Lines = new StripeList<InvoiceLineItem> { Data = new List<InvoiceLineItem> { new() { Amount = 5000 } } },
+            PeriodEnd = DateTime.UtcNow
         };
 
         _pricingClient.ListPremiumPlans().Returns(premiumPlans);
@@ -349,11 +373,15 @@ public class PreviewPremiumUpgradeProrationCommandTests
         // Act
         await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
-        // Assert - Verify both password manager and storage items are marked as deleted
+        // Assert - Verify password manager item is modified and storage item is deleted
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
             Arg.Is<InvoiceCreatePreviewOptions>(options =>
+                // Password manager item should be modified to new plan price, not deleted
                 options.SubscriptionDetails.Items.Any(item =>
-                    item.Id == "si_password_manager" && item.Deleted == true) &&
+                    item.Id == "si_password_manager" &&
+                    item.Price == targetPlan.PasswordManager.StripeSeatPlanId &&
+                    item.Deleted != true) &&
+                // Storage item should be deleted
                 options.SubscriptionDetails.Items.Any(item =>
                     item.Id == "si_storage" && item.Deleted == true)));
     }
@@ -394,7 +422,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             {
                 Data = new List<SubscriptionItem>
                 {
-                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" } }
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = DateTime.UtcNow.AddMonths(1) }
                 }
             }
         };
@@ -404,7 +432,9 @@ public class PreviewPremiumUpgradeProrationCommandTests
         var invoice = new Invoice
         {
             Total = 5000,
-            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } }
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } },
+            Lines = new StripeList<InvoiceLineItem> { Data = new List<InvoiceLineItem> { new() { Amount = 5000 } } },
+            PeriodEnd = DateTime.UtcNow
         };
 
         _pricingClient.ListPremiumPlans().Returns(premiumPlans);
@@ -417,10 +447,11 @@ public class PreviewPremiumUpgradeProrationCommandTests
         // Act
         await _command.Run(user, PlanType.FamiliesAnnually, billingAddress);
 
-        // Assert - Verify non-seat-based plan uses StripePlanId with quantity 1
+        // Assert - Verify non-seat-based plan uses StripePlanId with quantity 1 and modifies existing item
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
             Arg.Is<InvoiceCreatePreviewOptions>(options =>
                 options.SubscriptionDetails.Items.Any(item =>
+                    item.Id == "si_premium" &&
                     item.Price == targetPlan.PasswordManager.StripePlanId &&
                     item.Quantity == 1)));
     }
@@ -463,7 +494,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             {
                 Data = new List<SubscriptionItem>
                 {
-                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" } }
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = DateTime.UtcNow.AddMonths(1) }
                 }
             }
         };
@@ -473,7 +504,9 @@ public class PreviewPremiumUpgradeProrationCommandTests
         var invoice = new Invoice
         {
             Total = 5000,
-            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } }
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } },
+            Lines = new StripeList<InvoiceLineItem> { Data = new List<InvoiceLineItem> { new() { Amount = 5000 } } },
+            PeriodEnd = DateTime.UtcNow
         };
 
         _pricingClient.ListPremiumPlans().Returns(premiumPlans);
@@ -494,7 +527,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
                 options.Subscription == "sub_123" &&
                 options.CustomerDetails.Address.Country == "US" &&
                 options.CustomerDetails.Address.PostalCode == "12345" &&
-                options.SubscriptionDetails.ProrationBehavior == "create_prorations"));
+                options.SubscriptionDetails.ProrationBehavior == "always_invoice"));
     }
 
     [Theory, BitAutoData]
@@ -533,7 +566,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             {
                 Data = new List<SubscriptionItem>
                 {
-                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" } }
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = DateTime.UtcNow.AddMonths(1) }
                 }
             }
         };
@@ -544,7 +577,9 @@ public class PreviewPremiumUpgradeProrationCommandTests
         var invoice = new Invoice
         {
             Total = 5000,
-            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } }
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } },
+            Lines = new StripeList<InvoiceLineItem> { Data = new List<InvoiceLineItem> { new() { Amount = 5000 } } },
+            PeriodEnd = DateTime.UtcNow
         };
 
         _pricingClient.ListPremiumPlans().Returns(premiumPlans);
@@ -557,11 +592,186 @@ public class PreviewPremiumUpgradeProrationCommandTests
         // Act
         await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
-        // Assert - Verify seat-based plan uses StripeSeatPlanId with quantity 1
+        // Assert - Verify seat-based plan uses StripeSeatPlanId with quantity 1 and modifies existing item
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
             Arg.Is<InvoiceCreatePreviewOptions>(options =>
                 options.SubscriptionDetails.Items.Any(item =>
+                    item.Id == "si_premium" &&
                     item.Price == targetPlan.PasswordManager.StripeSeatPlanId &&
                     item.Quantity == 1)));
     }
+
+    [Theory]
+    [InlineData(0, 1)]     // Less than 15 days, minimum 1 month
+    [InlineData(1, 1)]     // 1 day = 1 month minimum
+    [InlineData(14, 1)]    // 14 days = 1 month minimum
+    [InlineData(15, 1)]    // 15 days rounds to 1 month
+    [InlineData(30, 1)]    // 30 days = 1 month
+    [InlineData(44, 1)]    // 44 days rounds to 1 month
+    [InlineData(45, 2)]    // 45 days rounds to 2 months
+    [InlineData(60, 2)]    // 60 days = 2 months
+    [InlineData(90, 3)]    // 90 days = 3 months
+    [InlineData(180, 6)]   // 180 days = 6 months
+    [InlineData(365, 12)]  // 365 days rounds to 12 months
+    public async Task Run_ValidUpgrade_CalculatesNewPlanProratedMonthsCorrectly(int daysRemaining, int expectedMonths)
+    {
+        // Arrange
+        var user = new User
+        {
+            Premium = true,
+            GatewaySubscriptionId = "sub_123",
+            GatewayCustomerId = "cus_123"
+        };
+        var billingAddress = new Core.Billing.Payment.Models.BillingAddress
+        {
+            Country = "US",
+            PostalCode = "12345"
+        };
+
+        var premiumPlan = new PremiumPlan
+        {
+            Name = "Premium",
+            Available = true,
+            LegacyYear = null,
+            Seat = new Bit.Core.Billing.Pricing.Premium.Purchasable
+            {
+                StripePriceId = "premium-annually",
+                Price = 10m,
+                Provided = 1
+            },
+            Storage = new Bit.Core.Billing.Pricing.Premium.Purchasable
+            {
+                StripePriceId = "storage-gb-annually",
+                Price = 4m,
+                Provided = 1
+            }
+        };
+        var premiumPlans = new List<PremiumPlan> { premiumPlan };
+
+        // Use fixed time to avoid DateTime.UtcNow differences
+        var now = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        var currentPeriodEnd = now.AddDays(daysRemaining);
+        var currentSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Customer = new Customer { Id = "cus_123", Discount = null },
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = currentPeriodEnd }
+                }
+            }
+        };
+
+        var targetPlan = new TeamsPlan(isAnnual: true);
+
+        var invoice = new Invoice
+        {
+            Total = 5000,
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } },
+            Lines = new StripeList<InvoiceLineItem>
+            {
+                Data = new List<InvoiceLineItem> { new() { Amount = 5000 } }
+            },
+            PeriodEnd = now
+        };
+
+        _pricingClient.ListPremiumPlans().Returns(premiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(targetPlan);
+        _stripeAdapter.GetSubscriptionAsync("sub_123", Arg.Any<SubscriptionGetOptions>())
+            .Returns(currentSubscription);
+        _stripeAdapter.CreateInvoicePreviewAsync(Arg.Any<InvoiceCreatePreviewOptions>())
+            .Returns(invoice);
+
+        // Act
+        var result = await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
+
+        // Assert
+        Assert.True(result.IsT0);
+        var proration = result.AsT0;
+        Assert.Equal(expectedMonths, proration.NewPlanProratedMonths);
+    }
+
+    [Theory, BitAutoData]
+    public async Task Run_ValidUpgrade_ReturnsNewPlanProratedAmountCorrectly(User user, BillingAddress billingAddress)
+    {
+        // Arrange
+        user.Premium = true;
+        user.GatewaySubscriptionId = "sub_123";
+        user.GatewayCustomerId = "cus_123";
+
+        var premiumPlan = new PremiumPlan
+        {
+            Name = "Premium",
+            Available = true,
+            LegacyYear = null,
+            Seat = new Bit.Core.Billing.Pricing.Premium.Purchasable
+            {
+                StripePriceId = "premium-annually",
+                Price = 10m,
+                Provided = 1
+            },
+            Storage = new Bit.Core.Billing.Pricing.Premium.Purchasable
+            {
+                StripePriceId = "storage-gb-annually",
+                Price = 4m,
+                Provided = 1
+            }
+        };
+        var premiumPlans = new List<PremiumPlan> { premiumPlan };
+
+        var now = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        var currentPeriodEnd = now.AddMonths(3);
+        var currentSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Customer = new Customer { Id = "cus_123", Discount = null },
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new() { Id = "si_premium", Price = new Price { Id = "premium-annually" }, CurrentPeriodEnd = currentPeriodEnd }
+                }
+            }
+        };
+
+        var targetPlan = new TeamsPlan(isAnnual: true);
+
+        // Invoice showing new plan cost, credit, and net
+        var invoice = new Invoice
+        {
+            Total = 4500, // $45.00 net after $5 credit
+            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 450 } }, // $4.50
+            Lines = new StripeList<InvoiceLineItem>
+            {
+                Data = new List<InvoiceLineItem>
+                {
+                    new() { Amount = -500 },  // -$5.00 credit
+                    new() { Amount = 5000 }   // $50.00 for new plan
+                }
+            },
+            PeriodEnd = now
+        };
+
+        _pricingClient.ListPremiumPlans().Returns(premiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(targetPlan);
+        _stripeAdapter.GetSubscriptionAsync("sub_123", Arg.Any<SubscriptionGetOptions>())
+            .Returns(currentSubscription);
+        _stripeAdapter.CreateInvoicePreviewAsync(Arg.Any<InvoiceCreatePreviewOptions>())
+            .Returns(invoice);
+
+        // Act
+        var result = await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
+
+        // Assert
+        Assert.True(result.IsT0);
+        var proration = result.AsT0;
+
+        Assert.Equal(50.00m, proration.NewPlanProratedAmount);
+        Assert.Equal(5.00m, proration.Credit);
+        Assert.Equal(4.50m, proration.Tax);
+        Assert.Equal(45.00m, proration.Total);
+    }
 }
+

test/Core.Test/Billing/Premium/Commands/UpgradePremiumToOrganizationCommandTests.cs

@@ -256,9 +256,8 @@ public class UpgradePremiumToOrganizationCommandTests
         await _stripeAdapter.Received(1).UpdateSubscriptionAsync(
             "sub_123",
             Arg.Is<SubscriptionUpdateOptions>(opts =>
-                opts.Items.Count == 2 && // 1 deleted + 1 seat (no storage)
+                opts.Items.Count == 1 && // Only 1 item: modify existing password manager item (no storage to delete)
-                opts.Items.Any(i => i.Deleted == true) &&
+                opts.Items.Any(i => i.Id == "si_premium" && i.Price == "teams-seat-annually" && i.Quantity == 1 && i.Deleted != true)));
-                opts.Items.Any(i => i.Price == "teams-seat-annually" && i.Quantity == 1)));
 
         await _organizationRepository.Received(1).CreateAsync(Arg.Is<Organization>(o =>
             o.Name == "My Organization" &&
@@ -331,9 +330,8 @@ public class UpgradePremiumToOrganizationCommandTests
         await _stripeAdapter.Received(1).UpdateSubscriptionAsync(
             "sub_123",
             Arg.Is<SubscriptionUpdateOptions>(opts =>
-                opts.Items.Count == 2 && // 1 deleted + 1 plan
+                opts.Items.Count == 1 && // Only 1 item: modify existing password manager item (no storage to delete)
-                opts.Items.Any(i => i.Deleted == true) &&
+                opts.Items.Any(i => i.Id == "si_premium" && i.Price == "families-plan-annually" && i.Quantity == 1 && i.Deleted != true)));
-                opts.Items.Any(i => i.Price == "families-plan-annually" && i.Quantity == 1)));
 
         await _organizationRepository.Received(1).CreateAsync(Arg.Is<Organization>(o =>
             o.Name == "My Families Org"));
@@ -461,14 +459,13 @@ public class UpgradePremiumToOrganizationCommandTests
         // Assert
         Assert.True(result.IsT0);
 
-        // Verify that BOTH legacy items (password manager + storage) are deleted by ID
+        // Verify that legacy password manager item is modified and legacy storage is deleted
         await _stripeAdapter.Received(1).UpdateSubscriptionAsync(
             "sub_123",
             Arg.Is<SubscriptionUpdateOptions>(opts =>
-                opts.Items.Count == 3 && // 2 deleted (legacy PM + legacy storage) + 1 new seat
+                opts.Items.Count == 2 && // 1 modified (legacy PM to new price) + 1 deleted (legacy storage)
-                opts.Items.Count(i => i.Deleted == true && i.Id == "si_premium_legacy") == 1 && // Legacy PM deleted
+                opts.Items.Count(i => i.Id == "si_premium_legacy" && i.Price == "teams-seat-annually" && i.Quantity == 1 && i.Deleted != true) == 1 && // Legacy PM modified
-                opts.Items.Count(i => i.Deleted == true && i.Id == "si_storage_legacy") == 1 && // Legacy storage deleted
+                opts.Items.Count(i => i.Deleted == true && i.Id == "si_storage_legacy") == 1)); // Legacy storage deleted
-                opts.Items.Any(i => i.Price == "teams-seat-annually" && i.Quantity == 1)));
     }
 
     [Theory, BitAutoData]
@@ -528,15 +525,14 @@ public class UpgradePremiumToOrganizationCommandTests
         // Assert
         Assert.True(result.IsT0);
 
-        // Verify that ONLY the premium password manager item is deleted (not other products)
+        // Verify that ONLY the premium password manager item is modified (not other products)
-        // Note: We delete the specific premium item by ID, so other products are untouched
+        // Note: We modify the specific premium item by ID, so other products are untouched
         await _stripeAdapter.Received(1).UpdateSubscriptionAsync(
             "sub_123",
             Arg.Is<SubscriptionUpdateOptions>(opts =>
-                opts.Items.Count == 2 && // 1 deleted (premium password manager) + 1 new seat
+                opts.Items.Count == 1 && // Only modify premium password manager item
-                opts.Items.Count(i => i.Deleted == true && i.Id == "si_premium") == 1 && // Premium item deleted by ID
+                opts.Items.Count(i => i.Id == "si_premium" && i.Price == "teams-seat-annually" && i.Quantity == 1 && i.Deleted != true) == 1 && // Premium item modified
-                opts.Items.Count(i => i.Id == "si_other_product") == 0 && // Other product NOT in update (untouched)
+                opts.Items.Count(i => i.Id == "si_other_product") == 0)); // Other product NOT in update (untouched)
-                opts.Items.Any(i => i.Price == "teams-seat-annually" && i.Quantity == 1)));
     }
 
     [Theory, BitAutoData]
@@ -603,8 +599,8 @@ public class UpgradePremiumToOrganizationCommandTests
             Arg.Is<SubscriptionUpdateOptions>(opts =>
                 opts.Metadata.ContainsKey(StripeConstants.MetadataKeys.PreviousAdditionalStorage) &&
                 opts.Metadata[StripeConstants.MetadataKeys.PreviousAdditionalStorage] == "5" &&
-                opts.Items.Count == 3 && // 2 deleted (premium + storage) + 1 new seat
+                opts.Items.Count == 2 && // 1 modified (premium to new price) + 1 deleted (storage)
-                opts.Items.Count(i => i.Deleted == true) == 2));
+                opts.Items.Count(i => i.Deleted == true) == 1));
     }
 
     [Theory, BitAutoData]
@@ -647,77 +643,6 @@ public class UpgradePremiumToOrganizationCommandTests
         Assert.Equal("Premium subscription password manager item not found.", badRequest.Response);
     }
 
-    [Theory, BitAutoData]
-    public async Task Run_PlanWithTrialPeriod_SetsTrialEnd(User user)
-    {
-        // Arrange
-        user.Premium = true;
-        user.GatewaySubscriptionId = "sub_123";
-        user.GatewayCustomerId = "cus_123";
-
-        var currentPeriodEnd = DateTime.UtcNow.AddMonths(1);
-        var mockSubscription = new Subscription
-        {
-            Id = "sub_123",
-            Items = new StripeList<SubscriptionItem>
-            {
-                Data = new List<SubscriptionItem>
-                {
-                    new SubscriptionItem
-                    {
-                        Id = "si_premium",
-                        Price = new Price { Id = "premium-annually" },
-                        CurrentPeriodEnd = currentPeriodEnd
-                    }
-                }
-            },
-            Metadata = new Dictionary<string, string>()
-        };
-
-        var mockPremiumPlans = CreateTestPremiumPlansList();
-
-        // Create a plan with a trial period
-        var mockPlan = CreateTestPlan(
-            PlanType.TeamsAnnually,
-            stripeSeatPlanId: "teams-seat-annually",
-            trialPeriodDays: 7
-        );
-
-        // Capture the subscription update options to verify TrialEnd is set
-        SubscriptionUpdateOptions capturedOptions = null;
-
-        _stripeAdapter.GetSubscriptionAsync("sub_123")
-            .Returns(mockSubscription);
-        _pricingClient.ListPremiumPlans().Returns(mockPremiumPlans);
-        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(mockPlan);
-        _stripeAdapter.UpdateSubscriptionAsync(Arg.Any<string>(), Arg.Do<SubscriptionUpdateOptions>(opts => capturedOptions = opts))
-            .Returns(Task.FromResult(mockSubscription));
-        _organizationRepository.CreateAsync(Arg.Any<Organization>()).Returns(callInfo => Task.FromResult(callInfo.Arg<Organization>()));
-        _organizationApiKeyRepository.CreateAsync(Arg.Any<OrganizationApiKey>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationApiKey>()));
-        _organizationUserRepository.CreateAsync(Arg.Any<OrganizationUser>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationUser>()));
-        _applicationCacheService.UpsertOrganizationAbilityAsync(Arg.Any<Organization>()).Returns(Task.CompletedTask);
-        _userService.SaveUserAsync(user).Returns(Task.CompletedTask);
-
-        // Act
-        var testStartTime = DateTime.UtcNow;
-        var result = await _command.Run(user, "My Organization", "encrypted-key", PlanType.TeamsAnnually, CreateTestBillingAddress());
-        var testEndTime = DateTime.UtcNow;
-
-        // Assert
-        Assert.True(result.IsT0);
-
-        await _stripeAdapter.Received(1).UpdateSubscriptionAsync("sub_123", Arg.Any<SubscriptionUpdateOptions>());
-
-        Assert.NotNull(capturedOptions);
-        Assert.NotNull(capturedOptions.TrialEnd);
-
-        // TrialEnd is AnyOf<DateTime?, SubscriptionTrialEnd> - verify it's a DateTime
-        var trialEndDateTime = capturedOptions.TrialEnd.Value as DateTime?;
-        Assert.NotNull(trialEndDateTime);
-        Assert.True(trialEndDateTime.Value >= testStartTime.AddDays(7));
-        Assert.True(trialEndDateTime.Value <= testEndTime.AddDays(7));
-    }
-
     [Theory, BitAutoData]
     public async Task Run_UpdatesCustomerBillingAddress(User user)
     {
@@ -823,4 +748,272 @@ public class UpgradePremiumToOrganizationCommandTests
                 opts.AutomaticTax != null &&
                 opts.AutomaticTax.Enabled == true));
     }
+
+    [Theory, BitAutoData]
+    public async Task Run_UsesAlwaysInvoiceProrationBehavior(User user)
+    {
+        // Arrange
+        user.Premium = true;
+        user.GatewaySubscriptionId = "sub_123";
+        user.GatewayCustomerId = "cus_123";
+
+        var mockSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new SubscriptionItem
+                    {
+                        Id = "si_premium",
+                        Price = new Price { Id = "premium-annually" }
+                    }
+                }
+            },
+            Metadata = new Dictionary<string, string>()
+        };
+
+        var mockPremiumPlans = CreateTestPremiumPlansList();
+        var mockPlan = CreateTestPlan(PlanType.TeamsAnnually, stripeSeatPlanId: "teams-seat-annually");
+
+        _stripeAdapter.GetSubscriptionAsync("sub_123").Returns(mockSubscription);
+        _pricingClient.ListPremiumPlans().Returns(mockPremiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(mockPlan);
+        _stripeAdapter.UpdateSubscriptionAsync(Arg.Any<string>(), Arg.Any<SubscriptionUpdateOptions>()).Returns(mockSubscription);
+        _stripeAdapter.UpdateCustomerAsync(Arg.Any<string>(), Arg.Any<CustomerUpdateOptions>()).Returns(Task.FromResult(new Customer()));
+        _organizationRepository.CreateAsync(Arg.Any<Organization>()).Returns(callInfo => Task.FromResult(callInfo.Arg<Organization>()));
+        _organizationApiKeyRepository.CreateAsync(Arg.Any<OrganizationApiKey>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationApiKey>()));
+        _organizationUserRepository.CreateAsync(Arg.Any<OrganizationUser>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationUser>()));
+        _applicationCacheService.UpsertOrganizationAbilityAsync(Arg.Any<Organization>()).Returns(Task.CompletedTask);
+        _userService.SaveUserAsync(user).Returns(Task.CompletedTask);
+
+        // Act
+        var result = await _command.Run(user, "My Organization", "encrypted-key", PlanType.TeamsAnnually, CreateTestBillingAddress());
+
+        // Assert
+        Assert.True(result.IsT0);
+
+        await _stripeAdapter.Received(1).UpdateSubscriptionAsync(
+            "sub_123",
+            Arg.Is<SubscriptionUpdateOptions>(opts =>
+                opts.ProrationBehavior == "always_invoice"));
+    }
+
+    [Theory, BitAutoData]
+    public async Task Run_ModifiesExistingSubscriptionItem_NotDeleteAndRecreate(User user)
+    {
+        // Arrange
+        user.Premium = true;
+        user.GatewaySubscriptionId = "sub_123";
+        user.GatewayCustomerId = "cus_123";
+
+        var mockSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new SubscriptionItem
+                    {
+                        Id = "si_premium",
+                        Price = new Price { Id = "premium-annually" }
+                    }
+                }
+            },
+            Metadata = new Dictionary<string, string>()
+        };
+
+        var mockPremiumPlans = CreateTestPremiumPlansList();
+        var mockPlan = CreateTestPlan(PlanType.TeamsAnnually, stripeSeatPlanId: "teams-seat-annually");
+
+        _stripeAdapter.GetSubscriptionAsync("sub_123").Returns(mockSubscription);
+        _pricingClient.ListPremiumPlans().Returns(mockPremiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(mockPlan);
+        _stripeAdapter.UpdateSubscriptionAsync(Arg.Any<string>(), Arg.Any<SubscriptionUpdateOptions>()).Returns(mockSubscription);
+        _stripeAdapter.UpdateCustomerAsync(Arg.Any<string>(), Arg.Any<CustomerUpdateOptions>()).Returns(Task.FromResult(new Customer()));
+        _organizationRepository.CreateAsync(Arg.Any<Organization>()).Returns(callInfo => Task.FromResult(callInfo.Arg<Organization>()));
+        _organizationApiKeyRepository.CreateAsync(Arg.Any<OrganizationApiKey>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationApiKey>()));
+        _organizationUserRepository.CreateAsync(Arg.Any<OrganizationUser>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationUser>()));
+        _applicationCacheService.UpsertOrganizationAbilityAsync(Arg.Any<Organization>()).Returns(Task.CompletedTask);
+        _userService.SaveUserAsync(user).Returns(Task.CompletedTask);
+
+        // Act
+        var result = await _command.Run(user, "My Organization", "encrypted-key", PlanType.TeamsAnnually, CreateTestBillingAddress());
+
+        // Assert
+        Assert.True(result.IsT0);
+
+        // Verify that the subscription item was modified, not deleted
+        await _stripeAdapter.Received(1).UpdateSubscriptionAsync(
+            "sub_123",
+            Arg.Is<SubscriptionUpdateOptions>(opts =>
+                // Should have an item with the original ID being modified
+                opts.Items.Any(item =>
+                    item.Id == "si_premium" &&
+                    item.Price == "teams-seat-annually" &&
+                    item.Quantity == 1 &&
+                    item.Deleted != true)));
+    }
+
+    [Theory, BitAutoData]
+    public async Task Run_CreatesOrganizationWithCorrectSettings(User user)
+    {
+        // Arrange
+        user.Premium = true;
+        user.GatewaySubscriptionId = "sub_123";
+        user.GatewayCustomerId = "cus_123";
+
+        var mockSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new SubscriptionItem
+                    {
+                        Id = "si_premium",
+                        Price = new Price { Id = "premium-annually" }
+                    }
+                }
+            },
+            Metadata = new Dictionary<string, string>()
+        };
+
+        var mockPremiumPlans = CreateTestPremiumPlansList();
+        var mockPlan = CreateTestPlan(PlanType.TeamsAnnually, stripeSeatPlanId: "teams-seat-annually");
+
+        _stripeAdapter.GetSubscriptionAsync("sub_123").Returns(mockSubscription);
+        _pricingClient.ListPremiumPlans().Returns(mockPremiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(mockPlan);
+        _stripeAdapter.UpdateSubscriptionAsync(Arg.Any<string>(), Arg.Any<SubscriptionUpdateOptions>()).Returns(mockSubscription);
+        _stripeAdapter.UpdateCustomerAsync(Arg.Any<string>(), Arg.Any<CustomerUpdateOptions>()).Returns(Task.FromResult(new Customer()));
+        _organizationRepository.CreateAsync(Arg.Any<Organization>()).Returns(callInfo => Task.FromResult(callInfo.Arg<Organization>()));
+        _organizationApiKeyRepository.CreateAsync(Arg.Any<OrganizationApiKey>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationApiKey>()));
+        _organizationUserRepository.CreateAsync(Arg.Any<OrganizationUser>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationUser>()));
+        _applicationCacheService.UpsertOrganizationAbilityAsync(Arg.Any<Organization>()).Returns(Task.CompletedTask);
+        _userService.SaveUserAsync(user).Returns(Task.CompletedTask);
+
+        // Act
+        var result = await _command.Run(user, "My Organization", "encrypted-key", PlanType.TeamsAnnually, CreateTestBillingAddress());
+
+        // Assert
+        Assert.True(result.IsT0);
+
+        await _organizationRepository.Received(1).CreateAsync(
+            Arg.Is<Organization>(org =>
+                org.Name == "My Organization" &&
+                org.BillingEmail == user.Email &&
+                org.PlanType == PlanType.TeamsAnnually &&
+                org.Seats == 1 &&
+                org.Gateway == GatewayType.Stripe &&
+                org.GatewayCustomerId == "cus_123" &&
+                org.GatewaySubscriptionId == "sub_123" &&
+                org.Enabled == true));
+    }
+
+    [Theory, BitAutoData]
+    public async Task Run_CreatesOrganizationApiKeyWithCorrectType(User user)
+    {
+        // Arrange
+        user.Premium = true;
+        user.GatewaySubscriptionId = "sub_123";
+        user.GatewayCustomerId = "cus_123";
+
+        var mockSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new SubscriptionItem
+                    {
+                        Id = "si_premium",
+                        Price = new Price { Id = "premium-annually" }
+                    }
+                }
+            },
+            Metadata = new Dictionary<string, string>()
+        };
+
+        var mockPremiumPlans = CreateTestPremiumPlansList();
+        var mockPlan = CreateTestPlan(PlanType.TeamsAnnually, stripeSeatPlanId: "teams-seat-annually");
+
+        _stripeAdapter.GetSubscriptionAsync("sub_123").Returns(mockSubscription);
+        _pricingClient.ListPremiumPlans().Returns(mockPremiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(mockPlan);
+        _stripeAdapter.UpdateSubscriptionAsync(Arg.Any<string>(), Arg.Any<SubscriptionUpdateOptions>()).Returns(mockSubscription);
+        _stripeAdapter.UpdateCustomerAsync(Arg.Any<string>(), Arg.Any<CustomerUpdateOptions>()).Returns(Task.FromResult(new Customer()));
+        _organizationRepository.CreateAsync(Arg.Any<Organization>()).Returns(callInfo => Task.FromResult(callInfo.Arg<Organization>()));
+        _organizationApiKeyRepository.CreateAsync(Arg.Any<OrganizationApiKey>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationApiKey>()));
+        _organizationUserRepository.CreateAsync(Arg.Any<OrganizationUser>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationUser>()));
+        _applicationCacheService.UpsertOrganizationAbilityAsync(Arg.Any<Organization>()).Returns(Task.CompletedTask);
+        _userService.SaveUserAsync(user).Returns(Task.CompletedTask);
+
+        // Act
+        var result = await _command.Run(user, "My Organization", "encrypted-key", PlanType.TeamsAnnually, CreateTestBillingAddress());
+
+        // Assert
+        Assert.True(result.IsT0);
+
+        await _organizationApiKeyRepository.Received(1).CreateAsync(
+            Arg.Is<OrganizationApiKey>(apiKey =>
+                apiKey.Type == OrganizationApiKeyType.Default &&
+                !string.IsNullOrEmpty(apiKey.ApiKey)));
+    }
+
+    [Theory, BitAutoData]
+    public async Task Run_CreatesOrganizationUserAsOwnerWithAllPermissions(User user)
+    {
+        // Arrange
+        user.Premium = true;
+        user.GatewaySubscriptionId = "sub_123";
+        user.GatewayCustomerId = "cus_123";
+
+        var mockSubscription = new Subscription
+        {
+            Id = "sub_123",
+            Items = new StripeList<SubscriptionItem>
+            {
+                Data = new List<SubscriptionItem>
+                {
+                    new SubscriptionItem
+                    {
+                        Id = "si_premium",
+                        Price = new Price { Id = "premium-annually" }
+                    }
+                }
+            },
+            Metadata = new Dictionary<string, string>()
+        };
+
+        var mockPremiumPlans = CreateTestPremiumPlansList();
+        var mockPlan = CreateTestPlan(PlanType.TeamsAnnually, stripeSeatPlanId: "teams-seat-annually");
+
+        _stripeAdapter.GetSubscriptionAsync("sub_123").Returns(mockSubscription);
+        _pricingClient.ListPremiumPlans().Returns(mockPremiumPlans);
+        _pricingClient.GetPlanOrThrow(PlanType.TeamsAnnually).Returns(mockPlan);
+        _stripeAdapter.UpdateSubscriptionAsync(Arg.Any<string>(), Arg.Any<SubscriptionUpdateOptions>()).Returns(mockSubscription);
+        _stripeAdapter.UpdateCustomerAsync(Arg.Any<string>(), Arg.Any<CustomerUpdateOptions>()).Returns(Task.FromResult(new Customer()));
+        _organizationRepository.CreateAsync(Arg.Any<Organization>()).Returns(callInfo => Task.FromResult(callInfo.Arg<Organization>()));
+        _organizationApiKeyRepository.CreateAsync(Arg.Any<OrganizationApiKey>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationApiKey>()));
+        _organizationUserRepository.CreateAsync(Arg.Any<OrganizationUser>()).Returns(callInfo => Task.FromResult(callInfo.Arg<OrganizationUser>()));
+        _applicationCacheService.UpsertOrganizationAbilityAsync(Arg.Any<Organization>()).Returns(Task.CompletedTask);
+        _userService.SaveUserAsync(user).Returns(Task.CompletedTask);
+
+        // Act
+        var result = await _command.Run(user, "My Organization", "encrypted-key", PlanType.TeamsAnnually, CreateTestBillingAddress());
+
+        // Assert
+        Assert.True(result.IsT0);
+
+        await _organizationUserRepository.Received(1).CreateAsync(
+            Arg.Is<OrganizationUser>(orgUser =>
+                orgUser.UserId == user.Id &&
+                orgUser.Type == OrganizationUserType.Owner &&
+                orgUser.Status == OrganizationUserStatusType.Confirmed));
+    }
 }