diff --git a/src/Api/Billing/Controllers/PreviewInvoiceController.cs b/src/Api/Billing/Controllers/PreviewInvoiceController.cs
index d55e7299d6..b2e2dcbad9 100644
--- a/src/Api/Billing/Controllers/PreviewInvoiceController.cs
+++ b/src/Api/Billing/Controllers/PreviewInvoiceController.cs
@@ -63,11 +63,11 @@ public class PreviewInvoiceController(
         [BindNever] User user,
         [FromBody] PreviewPremiumUpgradeProrationRequest request)
     {
-        var (tierType, billingAddress) = request.ToDomain();
+        var (planType, billingAddress) = request.ToDomain();
 
         var result = await previewPremiumUpgradeProrationCommand.Run(
             user,
-            tierType,
+            planType,
             billingAddress);
 
         return Handle(result.Map(pair => new { pair.Tax, pair.Total, pair.Credit }));
diff --git a/src/Api/Billing/Models/Requests/Premium/UpgradePremiumToOrganizationRequest.cs b/src/Api/Billing/Models/Requests/Premium/UpgradePremiumToOrganizationRequest.cs
index 14375efc78..7e7bf3ef3a 100644
--- a/src/Api/Billing/Models/Requests/Premium/UpgradePremiumToOrganizationRequest.cs
+++ b/src/Api/Billing/Models/Requests/Premium/UpgradePremiumToOrganizationRequest.cs
@@ -1,5 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
+using Bit.Api.Billing.Models.Requests.Payment;
 using Bit.Core.Billing.Enums;
 
 namespace Bit.Api.Billing.Models.Requests.Premium;
@@ -14,24 +15,29 @@ public class UpgradePremiumToOrganizationRequest
 
     [Required]
     [JsonConverter(typeof(JsonStringEnumConverter))]
-    public ProductTierType Tier { get; set; }
+    public required ProductTierType TargetProductTierType { get; set; }
 
     [Required]
-    [JsonConverter(typeof(JsonStringEnumConverter))]
-    public PlanCadenceType Cadence { get; set; }
+    public required MinimalBillingAddressRequest BillingAddress { get; set; }
 
-    private PlanType PlanType =>
-        Tier switch
+    private PlanType PlanType
+    {
+        get
         {
-            ProductTierType.Families => PlanType.FamiliesAnnually,
-            ProductTierType.Teams => Cadence == PlanCadenceType.Monthly
-                ? PlanType.TeamsMonthly
-                : PlanType.TeamsAnnually,
-            ProductTierType.Enterprise => Cadence == PlanCadenceType.Monthly
-                ? PlanType.EnterpriseMonthly
-                : PlanType.EnterpriseAnnually,
-            _ => throw new InvalidOperationException("Cannot upgrade to an Organization subscription that isn't Families, Teams or Enterprise.")
-        };
+            if (TargetProductTierType is not (ProductTierType.Families or ProductTierType.Teams or ProductTierType.Enterprise))
+            {
+                throw new InvalidOperationException($"Cannot upgrade Premium subscription to {TargetProductTierType} plan.");
+            }
+
+            return TargetProductTierType switch
+            {
+                ProductTierType.Families => PlanType.FamiliesAnnually,
+                ProductTierType.Teams => PlanType.TeamsAnnually,
+                ProductTierType.Enterprise => PlanType.EnterpriseAnnually,
+                _ => throw new InvalidOperationException($"Unexpected ProductTierType: {TargetProductTierType}")
+            };
+        }
+    }
 
     public (string OrganizationName, string Key, PlanType PlanType) ToDomain() => (OrganizationName, Key, PlanType);
 }
diff --git a/src/Api/Billing/Models/Requests/PreviewInvoice/PreviewPremiumUpgradeProrationRequest.cs b/src/Api/Billing/Models/Requests/PreviewInvoice/PreviewPremiumUpgradeProrationRequest.cs
index e3c109a155..68d7a8d002 100644
--- a/src/Api/Billing/Models/Requests/PreviewInvoice/PreviewPremiumUpgradeProrationRequest.cs
+++ b/src/Api/Billing/Models/Requests/PreviewInvoice/PreviewPremiumUpgradeProrationRequest.cs
@@ -1,4 +1,5 @@
 using System.ComponentModel.DataAnnotations;
+using System.Text.Json.Serialization;
 using Bit.Api.Billing.Models.Requests.Payment;
 using Bit.Core.Billing.Enums;
 using Bit.Core.Billing.Payment.Models;
@@ -8,11 +9,31 @@ namespace Bit.Api.Billing.Models.Requests.PreviewInvoice;
 public record PreviewPremiumUpgradeProrationRequest
 {
     [Required]
+    [JsonConverter(typeof(JsonStringEnumConverter))]
     public required ProductTierType TargetProductTierType { get; set; }
 
     [Required]
     public required MinimalBillingAddressRequest BillingAddress { get; set; }
 
-    public (ProductTierType, BillingAddress) ToDomain() =>
-        (TargetProductTierType, BillingAddress.ToDomain());
+    private PlanType PlanType
+    {
+        get
+        {
+            if (TargetProductTierType is not (ProductTierType.Families or ProductTierType.Teams or ProductTierType.Enterprise))
+            {
+                throw new InvalidOperationException($"Cannot upgrade Premium subscription to {TargetProductTierType} plan.");
+            }
+
+            return TargetProductTierType switch
+            {
+                ProductTierType.Families => PlanType.FamiliesAnnually,
+                ProductTierType.Teams => PlanType.TeamsAnnually,
+                ProductTierType.Enterprise => PlanType.EnterpriseAnnually,
+                _ => throw new InvalidOperationException($"Unexpected ProductTierType: {TargetProductTierType}")
+            };
+        }
+    }
+
+    public (PlanType, BillingAddress) ToDomain() =>
+        (PlanType, BillingAddress.ToDomain());
 }
diff --git a/src/Core/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommand.cs b/src/Core/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommand.cs
index db5b907f8c..4c864677df 100644
--- a/src/Core/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommand.cs
+++ b/src/Core/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommand.cs
@@ -20,12 +20,12 @@ public interface IPreviewPremiumUpgradeProrationCommand
     /// Calculates the tax, total cost, and proration credit for upgrading a Premium subscription to an Organization plan.
     /// </summary>
     /// <param name="user">The user with an active Premium subscription.</param>
-    /// <param name="targetProductTierType">The target organization tier (Families, Teams, or Enterprise).</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>
     Task<BillingCommandResult<(decimal Tax, decimal Total, decimal Credit)>> Run(
         User user,
-        ProductTierType targetProductTierType,
+        PlanType targetPlanType,
         BillingAddress billingAddress);
 }
 
@@ -38,7 +38,7 @@ public class PreviewPremiumUpgradeProrationCommand(
 {
     public Task<BillingCommandResult<(decimal Tax, decimal Total, decimal Credit)>> Run(
         User user,
-        ProductTierType targetProductTierType,
+        PlanType targetPlanType,
         BillingAddress billingAddress) => HandleAsync<(decimal, decimal, decimal)>(async () =>
     {
         if (user is not { Premium: true, GatewaySubscriptionId: not null and not "" })
@@ -46,20 +46,6 @@ public class PreviewPremiumUpgradeProrationCommand(
             return new BadRequest("User does not have an active Premium subscription.");
         }
 
-        if (targetProductTierType is not (ProductTierType.Families or ProductTierType.Teams or ProductTierType.Enterprise))
-        {
-            return new BadRequest($"Cannot upgrade Premium subscription to {targetProductTierType} plan.");
-        }
-
-        // Convert ProductTierType to PlanType (for premium upgrade, the only choice is annual plans so we can assume that cadence)
-        var targetPlanType = targetProductTierType switch
-        {
-            ProductTierType.Families => PlanType.FamiliesAnnually,
-            ProductTierType.Teams => PlanType.TeamsAnnually,
-            ProductTierType.Enterprise => PlanType.EnterpriseAnnually,
-            _ => throw new InvalidOperationException($"Unexpected ProductTierType: {targetProductTierType}")
-        };
-
         // Hardcode seats to 1 for upgrade flow
         const int seats = 1;
 
@@ -128,7 +114,7 @@ public class PreviewPremiumUpgradeProrationCommand(
             SubscriptionDetails = new InvoiceSubscriptionDetailsOptions
             {
                 Items = subscriptionItems,
-                ProrationBehavior = StripeConstants.ProrationBehavior.AlwaysInvoice
+                ProrationBehavior = StripeConstants.ProrationBehavior.CreateProrations
             }
         };
 
diff --git a/src/Core/Billing/Premium/Commands/UpgradePremiumToOrganizationCommand.cs b/src/Core/Billing/Premium/Commands/UpgradePremiumToOrganizationCommand.cs
index 81bc5c9e2c..50f90808e2 100644
--- a/src/Core/Billing/Premium/Commands/UpgradePremiumToOrganizationCommand.cs
+++ b/src/Core/Billing/Premium/Commands/UpgradePremiumToOrganizationCommand.cs
@@ -74,7 +74,7 @@ public class UpgradePremiumToOrganizationCommand(
 
         if (passwordManagerItem == null)
         {
-            return new BadRequest("Premium subscription item not found.");
+            return new BadRequest("Premium subscription password manager item not found.");
         }
 
         var usersPremiumPlan = premiumPlans.First(p => p.Seat.StripePriceId == passwordManagerItem.Price.Id);
@@ -133,7 +133,7 @@ public class UpgradePremiumToOrganizationCommand(
         var subscriptionUpdateOptions = new SubscriptionUpdateOptions
         {
             Items = subscriptionItemOptions,
-            ProrationBehavior = StripeConstants.ProrationBehavior.None,
+            ProrationBehavior = StripeConstants.ProrationBehavior.CreateProrations,
             Metadata = new Dictionary<string, string>
             {
                 [StripeConstants.MetadataKeys.OrganizationId] = organizationId.ToString(),
@@ -145,6 +145,11 @@ public class UpgradePremiumToOrganizationCommand(
             }
         };
 
+        if (targetPlan.TrialPeriodDays.HasValue)
+        {
+            subscriptionUpdateOptions.TrialEnd = DateTime.UtcNow.AddDays((double)targetPlan.TrialPeriodDays);
+        }
+
         // Create the Organization entity
         var organization = new Organization
         {
diff --git a/test/Api.Test/Billing/Models/Requests/PreviewPremiumUpgradeProrationRequestTests.cs b/test/Api.Test/Billing/Models/Requests/PreviewPremiumUpgradeProrationRequestTests.cs
new file mode 100644
index 0000000000..5ed4182a5d
--- /dev/null
+++ b/test/Api.Test/Billing/Models/Requests/PreviewPremiumUpgradeProrationRequestTests.cs
@@ -0,0 +1,56 @@
+using Bit.Api.Billing.Models.Requests.Payment;
+using Bit.Api.Billing.Models.Requests.PreviewInvoice;
+using Bit.Core.Billing.Enums;
+using Xunit;
+
+namespace Bit.Api.Test.Billing.Models.Requests;
+
+public class PreviewPremiumUpgradeProrationRequestTests
+{
+    [Theory]
+    [InlineData(ProductTierType.Families, PlanType.FamiliesAnnually)]
+    [InlineData(ProductTierType.Teams, PlanType.TeamsAnnually)]
+    [InlineData(ProductTierType.Enterprise, PlanType.EnterpriseAnnually)]
+    public void ToDomain_ValidTierTypes_ReturnsPlanType(ProductTierType tierType, PlanType expectedPlanType)
+    {
+        // Arrange
+        var sut = new PreviewPremiumUpgradeProrationRequest
+        {
+            TargetProductTierType = tierType,
+            BillingAddress = new MinimalBillingAddressRequest
+            {
+                Country = "US",
+                PostalCode = "12345"
+            }
+        };
+
+        // Act
+        var (planType, billingAddress) = sut.ToDomain();
+
+        // Assert
+        Assert.Equal(expectedPlanType, planType);
+        Assert.Equal("US", billingAddress.Country);
+        Assert.Equal("12345", billingAddress.PostalCode);
+    }
+
+    [Theory]
+    [InlineData(ProductTierType.Free)]
+    [InlineData(ProductTierType.TeamsStarter)]
+    public void ToDomain_InvalidTierTypes_ThrowsInvalidOperationException(ProductTierType tierType)
+    {
+        // Arrange
+        var sut = new PreviewPremiumUpgradeProrationRequest
+        {
+            TargetProductTierType = tierType,
+            BillingAddress = new MinimalBillingAddressRequest
+            {
+                Country = "US",
+                PostalCode = "12345"
+            }
+        };
+
+        // Act & Assert
+        var exception = Assert.Throws<InvalidOperationException>(() => sut.ToDomain());
+        Assert.Contains($"Cannot upgrade Premium subscription to {tierType} plan", exception.Message);
+    }
+}
diff --git a/test/Api.Test/Billing/Models/Requests/UpgradePremiumToOrganizationRequestTests.cs b/test/Api.Test/Billing/Models/Requests/UpgradePremiumToOrganizationRequestTests.cs
new file mode 100644
index 0000000000..6a8e328bf3
--- /dev/null
+++ b/test/Api.Test/Billing/Models/Requests/UpgradePremiumToOrganizationRequestTests.cs
@@ -0,0 +1,60 @@
+using Bit.Api.Billing.Models.Requests.Payment;
+using Bit.Api.Billing.Models.Requests.Premium;
+using Bit.Core.Billing.Enums;
+using Xunit;
+
+namespace Bit.Api.Test.Billing.Models.Requests;
+
+public class UpgradePremiumToOrganizationRequestTests
+{
+    [Theory]
+    [InlineData(ProductTierType.Families, PlanType.FamiliesAnnually)]
+    [InlineData(ProductTierType.Teams, PlanType.TeamsAnnually)]
+    [InlineData(ProductTierType.Enterprise, PlanType.EnterpriseAnnually)]
+    public void ToDomain_ValidTierTypes_ReturnsPlanType(ProductTierType tierType, PlanType expectedPlanType)
+    {
+        // Arrange
+        var sut = new UpgradePremiumToOrganizationRequest
+        {
+            OrganizationName = "Test Organization",
+            Key = "encrypted-key",
+            TargetProductTierType = tierType,
+            BillingAddress = new MinimalBillingAddressRequest
+            {
+                Country = "US",
+                PostalCode = "12345"
+            }
+        };
+
+        // Act
+        var (organizationName, key, planType) = sut.ToDomain();
+
+        // Assert
+        Assert.Equal("Test Organization", organizationName);
+        Assert.Equal("encrypted-key", key);
+        Assert.Equal(expectedPlanType, planType);
+    }
+
+    [Theory]
+    [InlineData(ProductTierType.Free)]
+    [InlineData(ProductTierType.TeamsStarter)]
+    public void ToDomain_InvalidTierTypes_ThrowsInvalidOperationException(ProductTierType tierType)
+    {
+        // Arrange
+        var sut = new UpgradePremiumToOrganizationRequest
+        {
+            OrganizationName = "Test Organization",
+            Key = "encrypted-key",
+            TargetProductTierType = tierType,
+            BillingAddress = new MinimalBillingAddressRequest
+            {
+                Country = "US",
+                PostalCode = "12345"
+            }
+        };
+
+        // Act & Assert
+        var exception = Assert.Throws<InvalidOperationException>(() => sut.ToDomain());
+        Assert.Contains($"Cannot upgrade Premium subscription to {tierType} plan", exception.Message);
+    }
+}
diff --git a/test/Core.Test/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommandTests.cs b/test/Core.Test/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommandTests.cs
index a681797a82..475c458361 100644
--- a/test/Core.Test/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommandTests.cs
+++ b/test/Core.Test/Billing/Premium/Commands/PreviewPremiumUpgradeProrationCommandTests.cs
@@ -36,7 +36,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
         user.Premium = false;
 
         // Act
-        var result = await _command.Run(user, ProductTierType.Teams, billingAddress);
+        var result = await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert
         Assert.True(result.IsT1);
@@ -52,7 +52,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
         user.GatewaySubscriptionId = null;
 
         // Act
-        var result = await _command.Run(user, ProductTierType.Teams, billingAddress);
+        var result = await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert
         Assert.True(result.IsT1);
@@ -136,7 +136,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        var result = await _command.Run(user, ProductTierType.Teams, billingAddress);
+        var result = await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert
         Assert.True(result.IsT0);
@@ -212,7 +212,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        var result = await _command.Run(user, ProductTierType.Teams, billingAddress);
+        var result = await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert
         Assert.True(result.IsT0);
@@ -279,7 +279,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        await _command.Run(user, ProductTierType.Teams, billingAddress);
+        await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert - Verify that the subscription item quantity is always 1
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
@@ -289,82 +289,6 @@ public class PreviewPremiumUpgradeProrationCommandTests
                     item.Quantity == 1)));
     }
 
-    [Theory]
-    [InlineData(ProductTierType.Families, PlanType.FamiliesAnnually)]
-    [InlineData(ProductTierType.Teams, PlanType.TeamsAnnually)]
-    [InlineData(ProductTierType.Enterprise, PlanType.EnterpriseAnnually)]
-    public async Task Run_ProductTierTypeConversion_MapsToCorrectPlanType(
-        ProductTierType productTierType,
-        PlanType expectedPlanType)
-    {
-        // Arrange
-        var user = new User
-        {
-            Premium = true,
-            GatewaySubscriptionId = "sub_123",
-            GatewayCustomerId = "cus_123"
-        };
-        var billingAddress = new 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 };
-
-        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" } }
-                }
-            }
-        };
-
-        var targetPlan = new TeamsPlan(isAnnual: true);
-
-        var invoice = new Invoice
-        {
-            Total = 5000,
-            TotalTaxes = new List<InvoiceTotalTax> { new() { Amount = 500 } }
-        };
-
-        _pricingClient.ListPremiumPlans().Returns(premiumPlans);
-        _pricingClient.GetPlanOrThrow(expectedPlanType).Returns(targetPlan);
-        _stripeAdapter.GetSubscriptionAsync("sub_123", Arg.Any<SubscriptionGetOptions>())
-            .Returns(currentSubscription);
-        _stripeAdapter.CreateInvoicePreviewAsync(Arg.Any<InvoiceCreatePreviewOptions>())
-            .Returns(invoice);
-
-        // Act
-        await _command.Run(user, productTierType, billingAddress);
-
-        // Assert - Verify that the correct PlanType was used
-        await _pricingClient.Received(1).GetPlanOrThrow(expectedPlanType);
-    }
-
     [Theory, BitAutoData]
     public async Task Run_ValidUpgrade_DeletesPremiumSubscriptionItems(User user, BillingAddress billingAddress)
     {
@@ -423,7 +347,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        await _command.Run(user, ProductTierType.Teams, billingAddress);
+        await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert - Verify both password manager and storage items are marked as deleted
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
@@ -491,7 +415,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        await _command.Run(user, ProductTierType.Families, billingAddress);
+        await _command.Run(user, PlanType.FamiliesAnnually, billingAddress);
 
         // Assert - Verify non-seat-based plan uses StripePlanId with quantity 1
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
@@ -560,7 +484,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        await _command.Run(user, ProductTierType.Teams, billingAddress);
+        await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert - Verify all invoice preview options are correct
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
@@ -570,24 +494,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
                 options.Subscription == "sub_123" &&
                 options.CustomerDetails.Address.Country == "US" &&
                 options.CustomerDetails.Address.PostalCode == "12345" &&
-                options.SubscriptionDetails.ProrationBehavior == "always_invoice"));
-    }
-
-    [Theory, BitAutoData]
-    public async Task Run_TeamsStarterTierType_ReturnsBadRequest(User user, BillingAddress billingAddress)
-    {
-        // Arrange
-        user.Premium = true;
-        user.GatewaySubscriptionId = "sub_123";
-        user.GatewayCustomerId = "cus_123";
-
-        // Act
-        var result = await _command.Run(user, ProductTierType.TeamsStarter, billingAddress);
-
-        // Assert
-        Assert.True(result.IsT1);
-        var badRequest = result.AsT1;
-        Assert.Equal("Cannot upgrade Premium subscription to TeamsStarter plan.", badRequest.Response);
+                options.SubscriptionDetails.ProrationBehavior == "create_prorations"));
     }
 
     [Theory, BitAutoData]
@@ -648,7 +555,7 @@ public class PreviewPremiumUpgradeProrationCommandTests
             .Returns(invoice);
 
         // Act
-        await _command.Run(user, ProductTierType.Teams, billingAddress);
+        await _command.Run(user, PlanType.TeamsAnnually, billingAddress);
 
         // Assert - Verify seat-based plan uses StripeSeatPlanId with quantity 1
         await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
diff --git a/test/Core.Test/Billing/Premium/Commands/UpgradePremiumToOrganizationCommandTests.cs b/test/Core.Test/Billing/Premium/Commands/UpgradePremiumToOrganizationCommandTests.cs
index e686d04009..4ead5c12da 100644
--- a/test/Core.Test/Billing/Premium/Commands/UpgradePremiumToOrganizationCommandTests.cs
+++ b/test/Core.Test/Billing/Premium/Commands/UpgradePremiumToOrganizationCommandTests.cs
@@ -28,7 +28,8 @@ public class UpgradePremiumToOrganizationCommandTests
             string? stripePlanId = null,
             string? stripeSeatPlanId = null,
             string? stripePremiumAccessPlanId = null,
-            string? stripeStoragePlanId = null)
+            string? stripeStoragePlanId = null,
+            int? trialPeriodDays = null)
         {
             Type = planType;
             ProductTier = ProductTierType.Teams;
@@ -37,7 +38,7 @@ public class UpgradePremiumToOrganizationCommandTests
             NameLocalizationKey = "";
             DescriptionLocalizationKey = "";
             CanBeUsedByBusiness = true;
-            TrialPeriodDays = null;
+            TrialPeriodDays = trialPeriodDays;
             HasSelfHost = false;
             HasPolicies = false;
             HasGroups = false;
@@ -86,10 +87,9 @@ public class UpgradePremiumToOrganizationCommandTests
         string? stripePlanId = null,
         string? stripeSeatPlanId = null,
         string? stripePremiumAccessPlanId = null,
-        string? stripeStoragePlanId = null)
-    {
-        return new TestPlan(planType, stripePlanId, stripeSeatPlanId, stripePremiumAccessPlanId, stripeStoragePlanId);
-    }
+        string? stripeStoragePlanId = null,
+        int? trialPeriodDays = null) =>
+        new TestPlan(planType, stripePlanId, stripeSeatPlanId, stripePremiumAccessPlanId, stripeStoragePlanId, trialPeriodDays);
 
     private static PremiumPlan CreateTestPremiumPlan(
         string seatPriceId = "premium-annually",
@@ -643,4 +643,75 @@ public class UpgradePremiumToOrganizationCommandTests
         var badRequest = result.AsT1;
         Assert.Equal("Premium subscription 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);
+        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));
+    }
 }