[PM-19180] Calculate sales tax correctly for sponsored plans

src/Core/Billing/Models/Api/Requests/Organizations/PreviewOrganizationInvoiceRequestModel.cs

@@ -1,5 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using Bit.Core.Billing.Enums;
+using Bit.Core.Enums;
 
 namespace Bit.Core.Billing.Models.Api.Requests.Organizations;
 
@@ -20,6 +21,8 @@ public class OrganizationPasswordManagerRequestModel
 {
     public PlanType Plan { get; set; }
 
+    public PlanSponsorshipType? SponsoredPlan { get; set; }
+
     [Range(0, int.MaxValue)]
     public int Seats { get; set; }
 

src/Core/Services/Implementations/StripePaymentService.cs

@@ -1286,6 +1286,7 @@ public class StripePaymentService : IPaymentService
         string gatewaySubscriptionId)
     {
         var plan = await _pricingClient.GetPlanOrThrow(parameters.PasswordManager.Plan);
+        var isSponsored = parameters.PasswordManager.SponsoredPlan.HasValue;
 
         var options = new InvoiceCreatePreviewOptions
         {
@@ -1311,24 +1312,25 @@ public class StripePaymentService : IPaymentService
             },
         };
 
+        if (isSponsored)
+        {
+            var sponsoredPlan = Utilities.StaticStore.GetSponsoredPlan(parameters.PasswordManager.SponsoredPlan.Value);
+            options.SubscriptionDetails.Items.Add(
+                new() { Quantity = 1, Plan = sponsoredPlan.StripePlanId }
+            );
+        }
+        else
+        {
             if (plan.PasswordManager.HasAdditionalSeatsOption)
             {
                 options.SubscriptionDetails.Items.Add(
-                new()
+                    new() { Quantity = parameters.PasswordManager.Seats, Plan = plan.PasswordManager.StripeSeatPlanId }
-                {
-                    Quantity = parameters.PasswordManager.Seats,
-                    Plan = plan.PasswordManager.StripeSeatPlanId
-                }
                 );
             }
             else
             {
                 options.SubscriptionDetails.Items.Add(
-                new()
+                    new() { Quantity = 1, Plan = plan.PasswordManager.StripePlanId }
-                {
-                    Quantity = 1,
-                    Plan = plan.PasswordManager.StripePlanId
-                }
                 );
             }
 
@@ -1352,6 +1354,7 @@ public class StripePaymentService : IPaymentService
                     });
                 }
             }
+        }
 
         if (!string.IsNullOrWhiteSpace(parameters.TaxInformation.TaxId))
         {