diff --git a/invoicedapi/Entities/Coupon.cs b/invoicedapi/Entities/Coupon.cs
index 5b10fc7..009c7ea 100644
--- a/invoicedapi/Entities/Coupon.cs
+++ b/invoicedapi/Entities/Coupon.cs
@@ -48,7 +48,7 @@ protected override string EntityId()
         // Conditional Serialisation
         public bool ShouldSerializeId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);;
         }
 
         public bool ShouldSerializeObject()
@@ -58,32 +58,32 @@ public bool ShouldSerializeObject()
 
         public bool ShouldSerializeCurrency()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeValue()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeIsPercent()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeExclusive()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeExpirationDate()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeMaxRedemptions()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeCreatedAt()
diff --git a/invoicedapi/Entities/Customer.cs b/invoicedapi/Entities/Customer.cs
index 568e2cc..9318753 100644
--- a/invoicedapi/Entities/Customer.cs
+++ b/invoicedapi/Entities/Customer.cs
@@ -269,12 +269,12 @@ public bool ShouldSerializeNextChaseStep()
 
         public bool ShouldSerializeAutopayDelayDays()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializePaymentSource()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeSignUpUrl()
diff --git a/invoicedapi/Entities/Item.cs b/invoicedapi/Entities/Item.cs
index a9c9ee5..ce8263b 100644
--- a/invoicedapi/Entities/Item.cs
+++ b/invoicedapi/Entities/Item.cs
@@ -56,7 +56,7 @@ protected override string EntityId()
         // Conditional Serialisation
         public bool ShouldSerializeId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeObject()
@@ -66,37 +66,37 @@ public bool ShouldSerializeObject()
 
         public bool ShouldSerializeCurrency()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeUnitCost()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeTaxable()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeTaxes()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeAvalaraTaxCode()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeGlAccount()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeDiscountable()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeCreatedAt()
diff --git a/invoicedapi/Entities/Note.cs b/invoicedapi/Entities/Note.cs
index f734dc0..861383f 100644
--- a/invoicedapi/Entities/Note.cs
+++ b/invoicedapi/Entities/Note.cs
@@ -108,12 +108,12 @@ public bool ShouldSerializeCustomer()
 
         public bool ShouldSerializeCustomerId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeInvoiceId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeCreatedAt()
diff --git a/invoicedapi/Entities/PaymentPlan.cs b/invoicedapi/Entities/PaymentPlan.cs
index a0dfdd5..d585b7f 100644
--- a/invoicedapi/Entities/PaymentPlan.cs
+++ b/invoicedapi/Entities/PaymentPlan.cs
@@ -78,7 +78,7 @@ public bool ShouldSerializeStatus()
 
         public bool ShouldSerializeInstallments()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeApproval()
diff --git a/invoicedapi/Entities/PendingLineItem.cs b/invoicedapi/Entities/PendingLineItem.cs
index 7b69e6d..eb3cd6e 100644
--- a/invoicedapi/Entities/PendingLineItem.cs
+++ b/invoicedapi/Entities/PendingLineItem.cs
@@ -57,7 +57,7 @@ public bool ShouldSerializeId()
 
         public bool ShouldSerializeItem()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
     }
 }
\ No newline at end of file
diff --git a/invoicedapi/Entities/Plan.cs b/invoicedapi/Entities/Plan.cs
index 98c53b3..7832be2 100644
--- a/invoicedapi/Entities/Plan.cs
+++ b/invoicedapi/Entities/Plan.cs
@@ -55,7 +55,7 @@ public virtual bool HasStringId()
         // Conditional Serialisation
         public bool ShouldSerializeId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeObject()
@@ -65,42 +65,42 @@ public bool ShouldSerializeObject()
 
         public bool ShouldSerializeItem()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeCurrency()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeAmount()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializePricingMode()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeQuantityType()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeInterval()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeIntervalCount()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeTiers()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeCreatedAt()
diff --git a/invoicedapi/Entities/Subscription.cs b/invoicedapi/Entities/Subscription.cs
index da74f08..111bde0 100644
--- a/invoicedapi/Entities/Subscription.cs
+++ b/invoicedapi/Entities/Subscription.cs
@@ -129,7 +129,7 @@ public async Task<SubscriptionPreview> PreviewAsync()
 
         public bool ShouldSerializeId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeObject()
@@ -139,27 +139,27 @@ public bool ShouldSerializeObject()
 
         public bool ShouldSerializeCustomer()
         {
-            return CurrentOperation != "SaveAll";
+            return CurrentOperation != nameof(SaveAll) && CurrentOperation != nameof(SaveAllAsync);
         }
 
         public bool ShouldSerializePlan()
         {
-            return CurrentOperation != "SaveAll";
+            return CurrentOperation != nameof(SaveAll) && CurrentOperation != nameof(SaveAllAsync);
         }
 
         public bool ShouldSerializeCycles()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeStartDate()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeBillIn()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializePeriodStart()
@@ -174,7 +174,7 @@ public bool ShouldSerializePeriodEnd()
 
         public bool ShouldSerializeCancelAtPeriodEnd()
         {
-            return CurrentOperation != "Preview";
+            return CurrentOperation != nameof(Preview) && CurrentOperation != nameof(PreviewAsync);
         }
 
         public bool ShouldSerializeCanceledAt()
@@ -184,7 +184,7 @@ public bool ShouldSerializeCanceledAt()
 
         public bool ShouldSerializePaused()
         {
-            return CurrentOperation != "Preview";
+            return CurrentOperation != nameof(Preview) && CurrentOperation != nameof(PreviewAsync);
         }
 
         public bool ShouldSerializeStatus()
@@ -204,12 +204,12 @@ public bool ShouldSerializeContractPeriodEnd()
 
         public bool ShouldSerializeRenewalCycles()
         {
-            return CurrentOperation != "Preview";
+            return CurrentOperation != nameof(Preview) && CurrentOperation != nameof(PreviewAsync);
         }
 
         public bool ShouldSerializeRenewalMode()
         {
-            return CurrentOperation != "Preview";
+            return CurrentOperation != nameof(Preview) && CurrentOperation != nameof(PreviewAsync);
         }
 
         public bool ShouldSerializeRecurringTotal()
@@ -239,12 +239,12 @@ public bool ShouldSerializeUpdatedAt()
 
         public bool ShouldSerializeMetadata()
         {
-            return CurrentOperation != "Preview";
+            return CurrentOperation != nameof(Preview) && CurrentOperation != nameof(PreviewAsync);
         }
 
         public bool ShouldSerializePendingLineItems()
         {
-            return CurrentOperation == "Preview";
+            return CurrentOperation == nameof(Preview) || CurrentOperation == nameof(PreviewAsync);
         }
     }
 }
\ No newline at end of file
diff --git a/invoicedapi/Entities/Task.cs b/invoicedapi/Entities/Task.cs
index 310c560..a41a44c 100644
--- a/invoicedapi/Entities/Task.cs
+++ b/invoicedapi/Entities/Task.cs
@@ -51,7 +51,7 @@ public bool ShouldSerializeId()
 
         public bool ShouldSerializeCustomerId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeComplete()
diff --git a/invoicedapi/Entities/TaxRate.cs b/invoicedapi/Entities/TaxRate.cs
index d065e87..fc82f08 100644
--- a/invoicedapi/Entities/TaxRate.cs
+++ b/invoicedapi/Entities/TaxRate.cs
@@ -47,7 +47,7 @@ public virtual bool HasStringId()
         // Conditional Serialisation
         public bool ShouldSerializeId()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeObject()
@@ -57,22 +57,22 @@ public bool ShouldSerializeObject()
 
         public bool ShouldSerializeCurrency()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeValue()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeIsPercent()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeInclusive()
         {
-            return CurrentOperation == "Create";
+            return CurrentOperation == nameof(Create) || CurrentOperation == nameof(CreateAsync);
         }
 
         public bool ShouldSerializeCreatedAt()