diff --git a/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/FreeProductPaymentDetails.cs b/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/FreeProductPaymentDetails.cs
index 159a15d0..8fa95612 100644
--- a/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/FreeProductPaymentDetails.cs
+++ b/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/FreeProductPaymentDetails.cs
@@ -1,4 +1,5 @@
 using System.Runtime.Serialization;
+using System.Text.Json.Serialization;
 
 namespace CoffeeCard.Models.DataTransferObjects.v2.Purchase
 {
@@ -12,6 +13,9 @@ namespace CoffeeCard.Models.DataTransferObjects.v2.Purchase
     /// }
     /// </example>
     [KnownType(typeof(FreePurchasePaymentDetails))]
+    [JsonPolymorphic(TypeDiscriminatorPropertyName = "discriminator")]
+    [JsonDerivedType(typeof(FreePurchasePaymentDetails), typeDiscriminator: "FreePurchasePaymentDetails")]
+
     public class FreePurchasePaymentDetails : PaymentDetails
     {
         /// <summary>
diff --git a/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/MobilePayPaymentDetails.cs b/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/MobilePayPaymentDetails.cs
index 3fd4795d..765e7f77 100644
--- a/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/MobilePayPaymentDetails.cs
+++ b/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/MobilePayPaymentDetails.cs
@@ -1,6 +1,7 @@
 using Newtonsoft.Json;
 using System.ComponentModel.DataAnnotations;
 using System.Runtime.Serialization;
+using System.Text.Json.Serialization;
 
 namespace CoffeeCard.Models.DataTransferObjects.v2.Purchase
 {
@@ -16,6 +17,8 @@ namespace CoffeeCard.Models.DataTransferObjects.v2.Purchase
     /// }
     /// </example>
     [KnownType(typeof(MobilePayPaymentDetails))]
+    [JsonPolymorphic(TypeDiscriminatorPropertyName = "discriminator")]
+    [JsonDerivedType(typeof(MobilePayPaymentDetails), typeDiscriminator: "MobilePayPaymentDetails")]
     public class MobilePayPaymentDetails : PaymentDetails
     {
         /// <summary>
diff --git a/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/PaymentDetails.cs b/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/PaymentDetails.cs
index 1b72271e..43bf7ad2 100644
--- a/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/PaymentDetails.cs
+++ b/coffeecard/CoffeeCard.Models/DataTransferObjects/v2/Purchase/PaymentDetails.cs
@@ -1,10 +1,13 @@
 using System.ComponentModel.DataAnnotations;
 using System.Runtime.Serialization;
+using System.Text.Json.Serialization;
 
 namespace CoffeeCard.Models.DataTransferObjects.v2.Purchase
 {
     [KnownType(typeof(MobilePayPaymentDetails))]
     [KnownType(typeof(FreePurchasePaymentDetails))]
+    [JsonPolymorphic(TypeDiscriminatorPropertyName = "discriminator")]
+    [JsonDerivedType(typeof(PaymentDetails), typeDiscriminator: "PaymentDetails")]
     public abstract class PaymentDetails
     {
         /// <summary>