diff --git a/tap_quickbooks/quickbooks/__init__.py b/tap_quickbooks/quickbooks/__init__.py
index f54507d..1e83f58 100644
--- a/tap_quickbooks/quickbooks/__init__.py
+++ b/tap_quickbooks/quickbooks/__init__.py
@@ -269,6 +269,8 @@ def field_to_property_schema(field, mdata):  # pylint:disable=too-many-branches
 
     return property_schema, mdata
 
+class RetriableApiError(Exception):
+    pass
 
 class Quickbooks():
     # pylint: disable=too-many-instance-attributes,too-many-arguments
@@ -370,7 +372,7 @@ def check_rest_quota_usage(self, headers):
 
     # pylint: disable=too-many-arguments
     @backoff.on_exception(backoff.expo,
-                          requests.exceptions.ConnectionError,
+                          (requests.exceptions.ConnectionError,RetriableApiError),
                           max_tries=10,
                           factor=2,
                           on_backoff=log_backoff_attempt)
@@ -384,6 +386,12 @@ def _make_request(self, http_method, url, headers=None, body=None, stream=False,
         else:
             raise TapQuickbooksException("Unsupported HTTP method")
 
+        if (
+            resp.status_code == 500
+            and resp.text
+            == "Authorization FailureAuthorizationFailure: Unknown Error during Authentication, statusCode: 500"
+        ) or resp.status_code in [400]:
+            raise RetriableApiError(resp.text)
         try:
             resp.raise_for_status()
         except RequestException as ex:
diff --git a/tap_quickbooks/quickbooks/rest_reports.py b/tap_quickbooks/quickbooks/rest_reports.py
index 0c5f4e1..96e7ab6 100644
--- a/tap_quickbooks/quickbooks/rest_reports.py
+++ b/tap_quickbooks/quickbooks/rest_reports.py
@@ -14,7 +14,7 @@ def is_fatal_code(e: requests.exceptions.RequestException) -> bool:
     '''Helper function to determine if a Requests reponse status code
     is a "fatal" status code. If it is, the backoff decorator will giveup
     instead of attemtping to backoff.'''
-    return 400 <= e.response.status_code < 500 and e.response.status_code != 429
+    return 400 <= e.response.status_code < 500 and e.response.status_code not in [429, 400]
 
 class RetriableException(Exception):
     pass