diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5fd6eac7..b1239f41 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,7 @@
 # Changelog
 
 ## Version 3.1.0
-- Incoproate changes for Advanced Commerce API, Retention Messaging API 1.5 and App Store Server API v1.21 [https://github.com/apple/app-store-server-library-python/pull/188] [https://github.com/apple/app-store-server-library-python/pull/189] from @riyazpanjwani
+- Incorporate changes for Advanced Commerce API, Retention Messaging API 1.5 and App Store Server API v1.21 [https://github.com/apple/app-store-server-library-python/pull/188] [https://github.com/apple/app-store-server-library-python/pull/189] from @riyazpanjwani
 - Incorporate changes for App Store Server API v1.20 [https://github.com/apple/app-store-server-library-python/pull/191] from @riyazpanjwani
 - Incorporate changes for Retention Messaging API v1.3 and 1.4 [https://github.com/apple/app-store-server-library-python/pull/186]
 - Fix deliveryStatus not being included in consumption information [https://github.com/apple/app-store-server-library-python/pull/184] from @ohadbenita
diff --git a/appstoreserverlibrary/models/LibraryUtility.py b/appstoreserverlibrary/models/LibraryUtility.py
index 253d446f..0ee535d8 100644
--- a/appstoreserverlibrary/models/LibraryUtility.py
+++ b/appstoreserverlibrary/models/LibraryUtility.py
@@ -97,6 +97,8 @@ def make_overrides(cl):
                         cattrs_overrides[raw_field] = override(rename=matching_name)
                     else:
                         cattrs_overrides[raw_field] = override(rename=matching_name, omit_if_default=True)
+            elif not attribute.init and attribute.name not in cattrs_overrides:
+                cattrs_overrides[attribute.name] = override(omit=False)
             elif attribute.default is None and attribute.name not in cattrs_overrides:
                 cattrs_overrides[attribute.name] = override(omit_if_default=True)
         return cattrs_overrides
diff --git a/tests/resources/models/advancedCommerceOneTimeChargeCreateRequest.json b/tests/resources/models/advancedCommerceOneTimeChargeCreateRequest.json
index d9874797..b81f2783 100644
--- a/tests/resources/models/advancedCommerceOneTimeChargeCreateRequest.json
+++ b/tests/resources/models/advancedCommerceOneTimeChargeCreateRequest.json
@@ -10,7 +10,5 @@
     "requestReferenceId": "550e8400-e29b-41d4-a716-446655440000"
   },
   "taxCode": "taxCode",
-  "storefront": "USA",
-  "operation": "CREATE",
-  "version": "1.0"
+  "storefront": "USA"
 }
diff --git a/tests/test_advanced_commerce_models.py b/tests/test_advanced_commerce_models.py
index 88ec27cd..93e2315d 100644
--- a/tests/test_advanced_commerce_models.py
+++ b/tests/test_advanced_commerce_models.py
@@ -622,6 +622,46 @@ def test_advanced_commerce_subscription_migrate_response_deserialization(self):
         self.assertEqual("signed_renewal_info_value", response.signedRenewalInfo)
         self.assertEqual("signed_transaction_info_value", response.signedTransactionInfo)
 
+    def test_one_time_charge_create_request_deserialization_sets_operation_and_version(self):
+        json_data = read_data_from_file('tests/resources/models/advancedCommerceOneTimeChargeCreateRequest.json')
+
+        request_dict = json.loads(json_data)
+        request = _get_cattrs_converter(AdvancedCommerceOneTimeChargeCreateRequest).structure(request_dict, AdvancedCommerceOneTimeChargeCreateRequest)
+
+        result = _get_cattrs_converter(AdvancedCommerceOneTimeChargeCreateRequest).unstructure(request)
+        self.assertEqual("CREATE_ONE_TIME_CHARGE", result["operation"])
+        self.assertEqual("1", result["version"])
+
+    def test_subscription_create_request_deserialization_sets_operation_and_version(self):
+        json_data = read_data_from_file('tests/resources/models/advancedCommerceSubscriptionCreateRequest.json')
+
+        request_dict = json.loads(json_data)
+        request = _get_cattrs_converter(AdvancedCommerceSubscriptionCreateRequest).structure(request_dict, AdvancedCommerceSubscriptionCreateRequest)
+
+        result = _get_cattrs_converter(AdvancedCommerceSubscriptionCreateRequest).unstructure(request)
+        self.assertEqual("CREATE_SUBSCRIPTION", result["operation"])
+        self.assertEqual("1", result["version"])
+
+    def test_subscription_modify_in_app_request_deserialization_sets_operation_and_version(self):
+        json_data = read_data_from_file('tests/resources/models/advancedCommerceSubscriptionModifyInAppRequest.json')
+
+        request_dict = json.loads(json_data)
+        request = _get_cattrs_converter(AdvancedCommerceSubscriptionModifyInAppRequest).structure(request_dict, AdvancedCommerceSubscriptionModifyInAppRequest)
+
+        result = _get_cattrs_converter(AdvancedCommerceSubscriptionModifyInAppRequest).unstructure(request)
+        self.assertEqual("MODIFY_SUBSCRIPTION", result["operation"])
+        self.assertEqual("1", result["version"])
+
+    def test_subscription_reactivate_in_app_request_deserialization_sets_operation_and_version(self):
+        json_data = read_data_from_file('tests/resources/models/advancedCommerceSubscriptionReactivateInAppRequest.json')
+
+        request_dict = json.loads(json_data)
+        request = _get_cattrs_converter(AdvancedCommerceSubscriptionReactivateInAppRequest).structure(request_dict, AdvancedCommerceSubscriptionReactivateInAppRequest)
+
+        result = _get_cattrs_converter(AdvancedCommerceSubscriptionReactivateInAppRequest).unstructure(request)
+        self.assertEqual("REACTIVATE_SUBSCRIPTION", result["operation"])
+        self.assertEqual("1", result["version"])
+
     def test_advanced_commerce_price_increase_info_status(self):
         self.assertEqual("SCHEDULED", AdvancedCommercePriceIncreaseInfoStatus.SCHEDULED.value)
         self.assertEqual("PENDING", AdvancedCommercePriceIncreaseInfoStatus.PENDING.value)