diff --git a/GoCardless/Resources/CreditorBankAccount.cs b/GoCardless/Resources/CreditorBankAccount.cs
index 85a4744..33097fd 100644
--- a/GoCardless/Resources/CreditorBankAccount.cs
+++ b/GoCardless/Resources/CreditorBankAccount.cs
@@ -47,7 +47,7 @@ public class CreditorBankAccount
         /// details](#local-bank-details-united-states) for more information.
         /// </summary>
         [JsonProperty("account_type")]
-        public string AccountType { get; set; }
+        public CreditorBankAccountAccountType? AccountType { get; set; }
 
         /// <summary>
         /// Name of bank, taken from the bank details.
diff --git a/GoCardless/Resources/CustomerBankAccount.cs b/GoCardless/Resources/CustomerBankAccount.cs
index 2323fe8..f989843 100644
--- a/GoCardless/Resources/CustomerBankAccount.cs
+++ b/GoCardless/Resources/CustomerBankAccount.cs
@@ -45,7 +45,7 @@ public class CustomerBankAccount
         /// details](#local-bank-details-united-states) for more information.
         /// </summary>
         [JsonProperty("account_type")]
-        public string AccountType { get; set; }
+        public CustomerBankAccountAccountType? AccountType { get; set; }
 
         /// <summary>
         /// Name of bank, taken from the bank details.
diff --git a/GoCardless/Services/CreditorBankAccountService.cs b/GoCardless/Services/CreditorBankAccountService.cs
index e1ad54d..91b316e 100644
--- a/GoCardless/Services/CreditorBankAccountService.cs
+++ b/GoCardless/Services/CreditorBankAccountService.cs
@@ -192,7 +192,7 @@ public class CreditorBankAccountCreateRequest : IHasIdempotencyKey
         /// details](#local-bank-details-united-states) for more information.
         /// </summary>
         [JsonProperty("account_type")]
-        public string AccountType { get; set; }
+        public CreditorBankAccountAccountType? AccountType { get; set; }
             
         /// <summary>
         /// Bank account type. Required for USD-denominated bank accounts. Must
diff --git a/GoCardless/Services/CustomerBankAccountService.cs b/GoCardless/Services/CustomerBankAccountService.cs
index 65f6317..f48760f 100644
--- a/GoCardless/Services/CustomerBankAccountService.cs
+++ b/GoCardless/Services/CustomerBankAccountService.cs
@@ -235,7 +235,7 @@ public class CustomerBankAccountCreateRequest : IHasIdempotencyKey
         /// details](#local-bank-details-united-states) for more information.
         /// </summary>
         [JsonProperty("account_type")]
-        public string AccountType { get; set; }
+        public CustomerBankAccountAccountType? AccountType { get; set; }
             
         /// <summary>
         /// Bank account type. Required for USD-denominated bank accounts. Must
diff --git a/GoCardless/Services/MandatePdfService.cs b/GoCardless/Services/MandatePdfService.cs
index 4bcfe7b..ec22898 100644
--- a/GoCardless/Services/MandatePdfService.cs
+++ b/GoCardless/Services/MandatePdfService.cs
@@ -165,7 +165,7 @@ public class MandatePdfCreateRequest
         /// details](#local-bank-details-united-states) for more information.
         /// </summary>
         [JsonProperty("account_type")]
-        public string AccountType { get; set; }
+        public MandatePdfAccountType? AccountType { get; set; }
             
         /// <summary>
         /// Bank account type. Required for USD-denominated bank accounts. Must
diff --git a/GoCardless/Services/RedirectFlowService.cs b/GoCardless/Services/RedirectFlowService.cs
index 33d6749..2f4474c 100644
--- a/GoCardless/Services/RedirectFlowService.cs
+++ b/GoCardless/Services/RedirectFlowService.cs
@@ -192,16 +192,16 @@ public class RedirectFlowPrefilledBankAccount
         {
 
             /// <summary>
-            /// Bank account type. Required for USD-denominated bank accounts.
-            /// Must not be provided for bank accounts in other currencies. See
-            /// [local details](#local-bank-details-united-states) for more
+            /// Bank account type for USD-denominated bank accounts. Must not be
+            /// provided for bank accounts in other currencies. See [local
+            /// details](#local-bank-details-united-states) for more
             /// information.
             /// </summary>
             [JsonProperty("account_type")]
             public RedirectFlowAccountType? AccountType { get; set; }
         /// <summary>
-        /// Bank account type. Required for USD-denominated bank accounts. Must
-        /// not be provided for bank accounts in other currencies. See [local
+        /// Bank account type for USD-denominated bank accounts. Must not be
+        /// provided for bank accounts in other currencies. See [local
         /// details](#local-bank-details-united-states) for more information.
         /// </summary>
         [JsonConverter(typeof(StringEnumConverter))]