diff --git a/api-ref/source/v2/parameters.yaml b/api-ref/source/v2/parameters.yaml
index 990a41736..e4dd9d9a4 100644
--- a/api-ref/source/v2/parameters.yaml
+++ b/api-ref/source/v2/parameters.yaml
@@ -5532,6 +5532,13 @@ quota:
   in: body
   required: true
   type: object
+quota-check-limit:
+  description: |
+    A flag used in the ``quota`` update command. If enabled, the Quota engine
+    will first check the resource usage before applying the new quota limit.
+  in: body
+  required: false
+  type: object
 quota-detail:
   description: |
     A ``quota`` detail object. Each key in the object corresponds to a resource
diff --git a/api-ref/source/v2/quotas.inc b/api-ref/source/v2/quotas.inc
index 4efa2cc0a..9fe1d2e67 100644
--- a/api-ref/source/v2/quotas.inc
+++ b/api-ref/source/v2/quotas.inc
@@ -114,6 +114,7 @@ Request
    - security_group_rule: quota-security_group_rule-request
    - subnet: quota-subnet-request
    - subnetpool: quota-subnetpool-request
+   - check_limit: quota-check-limit
 
 Request Example
 ---------------
diff --git a/api-ref/source/v2/samples/quotas/quotas-update-request.json b/api-ref/source/v2/samples/quotas/quotas-update-request.json
index 589bc8f5f..31e7aa27c 100644
--- a/api-ref/source/v2/samples/quotas/quotas-update-request.json
+++ b/api-ref/source/v2/samples/quotas/quotas-update-request.json
@@ -8,6 +8,7 @@
         "security_group": 10,
         "security_group_rule": 100,
         "subnet": 10,
-        "subnetpool": -1
+        "subnetpool": -1,
+        "check_limit": "True"
     }
 }
diff --git a/neutron_lib/api/definitions/__init__.py b/neutron_lib/api/definitions/__init__.py
index 8150ee7bb..91326c414 100644
--- a/neutron_lib/api/definitions/__init__.py
+++ b/neutron_lib/api/definitions/__init__.py
@@ -105,6 +105,7 @@ from neutron_lib.api.definitions import qos_pps_minimum_rule
 from neutron_lib.api.definitions import qos_pps_rule
 from neutron_lib.api.definitions import qos_rule_type_details
 from neutron_lib.api.definitions import qos_rules_alias
+from neutron_lib.api.definitions import quota_check_limit
 from neutron_lib.api.definitions import rbac_address_groups
 from neutron_lib.api.definitions import rbac_address_scope
 from neutron_lib.api.definitions import rbac_bgpvpn
@@ -240,6 +241,7 @@ _ALL_API_DEFINITIONS = {
     qos_pps_rule,
     qos_rule_type_details,
     qos_rules_alias,
+    quota_check_limit,
     rbac_address_groups,
     rbac_address_scope,
     rbac_bgpvpn,
diff --git a/neutron_lib/api/definitions/base.py b/neutron_lib/api/definitions/base.py
index f697b15a6..2a4f1b7e7 100644
--- a/neutron_lib/api/definitions/base.py
+++ b/neutron_lib/api/definitions/base.py
@@ -145,6 +145,7 @@ KNOWN_EXTENSIONS = (
     'qos-port-network-policy',
     'qos-rules-alias',
     'quotas',
+    'quota-check-limit',
     'rbac-address-group',
     'rbac-address-scope',
     'rbac-bgpvpn',
diff --git a/neutron_lib/api/definitions/quota_check_limit.py b/neutron_lib/api/definitions/quota_check_limit.py
new file mode 100644
index 000000000..4182a8a8f
--- /dev/null
+++ b/neutron_lib/api/definitions/quota_check_limit.py
@@ -0,0 +1,27 @@
+# Copyright 2021 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+ALIAS = 'quota-check-limit'
+IS_SHIM_EXTENSION = True
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Quota engine limit check'
+DESCRIPTION = ('Support for checking the resource usage before applying a new '
+               'quota limit')
+UPDATED_TIMESTAMP = '2021-09-08T16:00:00-00:00'
+RESOURCE_ATTRIBUTE_MAP = {}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = []
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}
diff --git a/neutron_lib/tests/unit/api/definitions/test_quota_check_limit.py b/neutron_lib/tests/unit/api/definitions/test_quota_check_limit.py
new file mode 100644
index 000000000..d7255a6a9
--- /dev/null
+++ b/neutron_lib/tests/unit/api/definitions/test_quota_check_limit.py
@@ -0,0 +1,20 @@
+# Copyright 2021 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from neutron_lib.api.definitions import quota_check_limit
+from neutron_lib.tests.unit.api.definitions import base
+
+
+class QuotaCheckLimitDefinitionTestCase(base.DefinitionBaseTestCase):
+    extension_module = quota_check_limit
diff --git a/releasenotes/notes/add-quota-check-limit-api-extension-8e39299644d41f74.yaml b/releasenotes/notes/add-quota-check-limit-api-extension-8e39299644d41f74.yaml
new file mode 100644
index 000000000..69535be6e
--- /dev/null
+++ b/releasenotes/notes/add-quota-check-limit-api-extension-8e39299644d41f74.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Add API extension ``quota-check-limit``. This is a shim extension that
+    indicates if Neutron supports checking the resource usage before applying
+    a new quota limit. A new API parameter ``check_limit`` is introduced; it
+    can be used in the ``quota`` update request to enable this check.