diff --git a/nova/api/openstack/placement/handler.py b/nova/api/openstack/placement/handler.py
index a54360ded556..38ed64c51310 100644
--- a/nova/api/openstack/placement/handler.py
+++ b/nova/api/openstack/placement/handler.py
@@ -100,9 +100,12 @@ ROUTE_DECLARATIONS = {
     '/resource_providers/{uuid}/allocations': {
         'GET': allocation.list_for_resource_provider,
     },
+    '/allocations': {
+        'POST': allocation.set_allocations,
+    },
     '/allocations/{consumer_uuid}': {
         'GET': allocation.list_for_consumer,
-        'PUT': allocation.set_allocations,
+        'PUT': allocation.set_allocations_for_consumer,
         'DELETE': allocation.delete_allocations,
     },
     '/allocation_candidates': {
diff --git a/nova/api/openstack/placement/handlers/allocation.py b/nova/api/openstack/placement/handlers/allocation.py
index 1504ff415597..cb5a7c528b72 100644
--- a/nova/api/openstack/placement/handlers/allocation.py
+++ b/nova/api/openstack/placement/handlers/allocation.py
@@ -138,6 +138,24 @@ ALLOCATION_SCHEMA_V1_12 = {
 }
 
 
+# POST to /allocations, added in microversion 1.13, uses the
+# POST_ALLOCATIONS_V1_13 schema to allow multiple allocations
+# from multiple consumers in one request. It is a dict, keyed by
+# consumer uuid, using the form of PUT allocations from microversion
+# 1.12. In POST the allocations can be empty, so DELETABLE_ALLOCATIONS
+# modifies ALLOCATION_SCHEMA_V1_12 accordingly.
+DELETABLE_ALLOCATIONS = copy.deepcopy(ALLOCATION_SCHEMA_V1_12)
+DELETABLE_ALLOCATIONS['properties']['allocations']['minProperties'] = 0
+POST_ALLOCATIONS_V1_13 = {
+    "type": "object",
+    "minProperties": 1,
+    "additionalProperties": False,
+    "patternProperties": {
+        "^[0-9a-fA-F-]{36}$": DELETABLE_ALLOCATIONS
+    }
+}
+
+
 def _allocations_dict(allocations, key_fetcher, resource_provider=None,
                       want_version=None):
     """Turn allocations into a dict of resources keyed by key_fetcher."""
@@ -277,7 +295,42 @@ def list_for_resource_provider(req):
     return req.response
 
 
-def _set_allocations(req, schema):
+def _new_allocations(context, resource_provider_uuid, consumer_uuid,
+                     resources, project_id, user_id):
+    """Create new allocation objects for a set of resources
+
+    Returns a list of Allocation objects.
+
+    :param context: The placement context.
+    :param resource_provider_uuid: The uuid of the resource provider that
+                                   has the resources.
+    :param consumer_uuid: The uuid of the consumer of the resources.
+    :param resources: A dict of resource classes and values.
+    :param project_id: The project consuming the resources.
+    :param user_id: The user consuming the resources.
+    """
+    allocations = []
+    try:
+        resource_provider = rp_obj.ResourceProvider.get_by_uuid(
+            context, resource_provider_uuid)
+    except exception.NotFound:
+        raise webob.exc.HTTPBadRequest(
+            _("Allocation for resource provider '%(rp_uuid)s' "
+              "that does not exist.") %
+            {'rp_uuid': resource_provider_uuid})
+    for resource_class in resources:
+        allocation = rp_obj.Allocation(
+            resource_provider=resource_provider,
+            consumer_id=consumer_uuid,
+            resource_class=resource_class,
+            project_id=project_id,
+            user_id=user_id,
+            used=resources[resource_class])
+        allocations.append(allocation)
+    return allocations
+
+
+def _set_allocations_for_consumer(req, schema):
     context = req.environ['placement.context']
     consumer_uuid = util.wsgi_path_item(req.environ, 'consumer_uuid')
     data = util.extract_json(req.body, schema)
@@ -299,25 +352,13 @@ def _set_allocations(req, schema):
     # that does not exist, raise a 400.
     allocation_objects = []
     for resource_provider_uuid, allocation in allocation_data.items():
-        try:
-            resource_provider = rp_obj.ResourceProvider.get_by_uuid(
-                context, resource_provider_uuid)
-        except exception.NotFound:
-            raise webob.exc.HTTPBadRequest(
-                _("Allocation for resource provider '%(rp_uuid)s' "
-                  "that does not exist.") %
-                {'rp_uuid': resource_provider_uuid})
-
-        resources = allocation['resources']
-        for resource_class in resources:
-            allocation = rp_obj.Allocation(
-                resource_provider=resource_provider,
-                consumer_id=consumer_uuid,
-                resource_class=resource_class,
-                project_id=data.get('project_id'),
-                user_id=data.get('user_id'),
-                used=resources[resource_class])
-            allocation_objects.append(allocation)
+        new_allocations = _new_allocations(context,
+                                           resource_provider_uuid,
+                                           consumer_uuid,
+                                           allocation['resources'],
+                                           data.get('project_id'),
+                                           data.get('user_id'))
+        allocation_objects.extend(new_allocations)
 
     allocations = rp_obj.AllocationList(
         context, objects=allocation_objects)
@@ -349,22 +390,84 @@ def _set_allocations(req, schema):
 @wsgi_wrapper.PlacementWsgify
 @microversion.version_handler('1.0', '1.7')
 @util.require_content('application/json')
-def set_allocations(req):
-    return _set_allocations(req, ALLOCATION_SCHEMA)
+def set_allocations_for_consumer(req):
+    return _set_allocations_for_consumer(req, ALLOCATION_SCHEMA)
 
 
 @wsgi_wrapper.PlacementWsgify  # noqa
 @microversion.version_handler('1.8', '1.11')
 @util.require_content('application/json')
-def set_allocations(req):
-    return _set_allocations(req, ALLOCATION_SCHEMA_V1_8)
+def set_allocations_for_consumer(req):
+    return _set_allocations_for_consumer(req, ALLOCATION_SCHEMA_V1_8)
 
 
 @wsgi_wrapper.PlacementWsgify  # noqa
 @microversion.version_handler('1.12')
 @util.require_content('application/json')
+def set_allocations_for_consumer(req):
+    return _set_allocations_for_consumer(req, ALLOCATION_SCHEMA_V1_12)
+
+
+@wsgi_wrapper.PlacementWsgify
+@microversion.version_handler('1.13')
+@util.require_content('application/json')
 def set_allocations(req):
-    return _set_allocations(req, ALLOCATION_SCHEMA_V1_12)
+    context = req.environ['placement.context']
+    data = util.extract_json(req.body, POST_ALLOCATIONS_V1_13)
+
+    # Create a sequence of allocation objects to be used in an
+    # AllocationList.create_all() call, which will mean all the changes
+    # happen within a single transaction and with resource provider
+    # generations check all in one go.
+    allocation_objects = []
+
+    for consumer_uuid in data:
+        project_id = data[consumer_uuid]['project_id']
+        user_id = data[consumer_uuid]['user_id']
+        allocations = data[consumer_uuid]['allocations']
+        if allocations:
+            for resource_provider_uuid in allocations:
+                resources = allocations[resource_provider_uuid]['resources']
+                new_allocations = _new_allocations(context,
+                                                   resource_provider_uuid,
+                                                   consumer_uuid,
+                                                   resources,
+                                                   project_id,
+                                                   user_id)
+                allocation_objects.extend(new_allocations)
+        else:
+            # The allocations are empty, which means wipe them out.
+            # Internal to the allocation object this is signalled by a
+            # used value of 0.
+            allocations = rp_obj.AllocationList.get_all_by_consumer_id(
+                context, consumer_uuid)
+            for allocation in allocations:
+                allocation.used = 0
+                allocation_objects.append(allocation)
+
+    allocations = rp_obj.AllocationList(
+        context, objects=allocation_objects)
+
+    try:
+        allocations.create_all()
+        LOG.debug("Successfully wrote allocations %s", allocations)
+    except exception.NotFound as exc:
+        raise webob.exc.HTTPBadRequest(
+            _("Unable to allocate inventory %(error)s") % {'error': exc})
+    except exception.InvalidInventory as exc:
+        # InvalidInventory is a parent for several exceptions that
+        # indicate either that Inventory is not present, or that
+        # capacity limits have been exceeded.
+        raise webob.exc.HTTPConflict(
+            _('Unable to allocate inventory: %(error)s') % {'error': exc})
+    except exception.ConcurrentUpdateDetected as exc:
+        raise webob.exc.HTTPConflict(
+            _('Inventory changed while attempting to allocate: %(error)s') %
+            {'error': exc})
+
+    req.response.status = 204
+    req.response.content_type = None
+    return req.response
 
 
 @wsgi_wrapper.PlacementWsgify
diff --git a/nova/api/openstack/placement/microversion.py b/nova/api/openstack/placement/microversion.py
index 410aab3bbe5d..210acca4027f 100644
--- a/nova/api/openstack/placement/microversion.py
+++ b/nova/api/openstack/placement/microversion.py
@@ -52,6 +52,7 @@ VERSIONS = [
     '1.12',  # Add project_id and user_id to GET /allocations/{consumer_uuid}
              # and PUT to /allocations/{consumer_uuid} in the same dict form
              # as GET
+    '1.13',  # Adds POST /allocations to set allocations for multiple consumers
 ]
 
 
diff --git a/nova/api/openstack/placement/rest_api_version_history.rst b/nova/api/openstack/placement/rest_api_version_history.rst
index ef2c61c6f7d4..b4a2c1827267 100644
--- a/nova/api/openstack/placement/rest_api_version_history.rst
+++ b/nova/api/openstack/placement/rest_api_version_history.rst
@@ -172,3 +172,9 @@ response body. Because the `PUT` request requires `user_id` and
 response. In addition, the response body for ``GET /allocation_candidates``
 is updated so the allocations in the ``alocation_requests`` object work
 with the new `PUT` format.
+
+1.13 POST multiple allocations to /allocations
+----------------------------------------------
+
+Version 1.13 gives the ability to set or clear allocations for more than
+one consumer uuid with a request to ``POST /allocations``.
diff --git a/nova/tests/functional/api/openstack/placement/fixtures.py b/nova/tests/functional/api/openstack/placement/fixtures.py
index cbd3518b1cf9..f419cd4f8d98 100644
--- a/nova/tests/functional/api/openstack/placement/fixtures.py
+++ b/nova/tests/functional/api/openstack/placement/fixtures.py
@@ -80,6 +80,11 @@ class APIFixture(fixture.GabbiFixture):
         os.environ['CUSTOM_RES_CLASS'] = 'CUSTOM_IRON_NFV'
         os.environ['PROJECT_ID'] = uuidutils.generate_uuid()
         os.environ['USER_ID'] = uuidutils.generate_uuid()
+        os.environ['PROJECT_ID_ALT'] = uuidutils.generate_uuid()
+        os.environ['USER_ID_ALT'] = uuidutils.generate_uuid()
+        os.environ['INSTANCE_UUID'] = uuidutils.generate_uuid()
+        os.environ['MIGRATION_UUID'] = uuidutils.generate_uuid()
+        os.environ['CONSUMER_UUID'] = uuidutils.generate_uuid()
 
     def stop_fixture(self):
         self.api_db_fixture.cleanup()
diff --git a/nova/tests/functional/api/openstack/placement/gabbits/allocations-post.yaml b/nova/tests/functional/api/openstack/placement/gabbits/allocations-post.yaml
new file mode 100644
index 000000000000..e1a7fdaf8732
--- /dev/null
+++ b/nova/tests/functional/api/openstack/placement/gabbits/allocations-post.yaml
@@ -0,0 +1,288 @@
+# Test that it possible to POST multiple allocations to /allocations to
+# simultaneously make changes, including removing resources for a consumer if
+# the allocations are empty.
+
+fixtures:
+    - APIFixture
+
+defaults:
+    request_headers:
+        x-auth-token: admin
+        accept: application/json
+        content-type: application/json
+        openstack-api-version: placement 1.13
+
+tests:
+
+- name: create compute one
+  POST: /resource_providers
+  data:
+      name: compute01
+  status: 201
+
+- name: rp compute01
+  desc: provide a reference for later reuse
+  GET: $LOCATION
+
+- name: create compute two
+  POST: /resource_providers
+  data:
+      name: compute02
+  status: 201
+
+- name: rp compute02
+  desc: provide a reference for later reuse
+  GET: $LOCATION
+
+- name: create shared disk
+  POST: /resource_providers
+  data:
+      name: storage01
+  status: 201
+
+- name: rp storage01
+  desc: provide a reference for later reuse
+  GET: $LOCATION
+
+- name: inventory compute01
+  PUT: $HISTORY['rp compute01'].$RESPONSE['links[?rel = "inventories"].href']
+  data:
+      resource_provider_generation: 0
+      inventories:
+          VCPU:
+              total: 16
+          MEMORY_MB:
+              total: 2048
+
+- name: inventory compute02
+  PUT: $HISTORY['rp compute02'].$RESPONSE['links[?rel = "inventories"].href']
+  data:
+      resource_provider_generation: 0
+      inventories:
+          VCPU:
+              total: 16
+          MEMORY_MB:
+              total: 2048
+
+- name: inventory storage01
+  PUT: $HISTORY['rp storage01'].$RESPONSE['links[?rel = "inventories"].href']
+  data:
+      resource_provider_generation: 0
+      inventories:
+          DISK_GB:
+              total: 4096
+
+- name: confirm only POST
+  GET: /allocations
+  status: 405
+  response_headers:
+      allow: POST
+
+- name: 404 on older 1.12 microversion post
+  POST: /allocations
+  request_headers:
+      openstack-api-version: placement 1.12
+  status: 404
+
+- name: post allocations two consumers
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+      $ENVIRON['MIGRATION_UUID']:
+          allocations:
+              $HISTORY['rp compute01'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+  status: 204
+
+- name: confirm usages
+  GET: /usages?project_id=$ENVIRON['PROJECT_ID']
+  response_json_paths:
+      $.usages.DISK_GB: 5
+      $.usages.VCPU: 4
+      $.usages.MEMORY_MB: 2048
+
+- name: clear and set allocations
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+      $ENVIRON['MIGRATION_UUID']:
+          allocations: {}
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+  status: 204
+
+- name: confirm usages after clear
+  GET: /usages?project_id=$ENVIRON['PROJECT_ID']
+  response_json_paths:
+      $.usages.DISK_GB: 5
+      $.usages.VCPU: 2
+      $.usages.MEMORY_MB: 1024
+
+- name: post allocations two users
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+      # We must use a fresh consumer id with the alternate project id info.
+      # A previously seen consumer id will be assumed to always have the same
+      # project and user.
+      $ENVIRON['CONSUMER_UUID']:
+          allocations:
+              $HISTORY['rp compute01'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+          project_id: $ENVIRON['PROJECT_ID_ALT']
+          user_id: $ENVIRON['USER_ID_ALT']
+  status: 204
+
+- name: confirm usages user a
+  GET: /usages?project_id=$ENVIRON['PROJECT_ID']
+  response_json_paths:
+      $.usages.`len`: 3
+      $.usages.DISK_GB: 5
+      $.usages.VCPU: 2
+      $.usages.MEMORY_MB: 1024
+
+- name: confirm usages user b
+  GET: /usages?project_id=$ENVIRON['PROJECT_ID_ALT']
+  response_json_paths:
+      $.usages.`len`: 2
+      $.usages.VCPU: 2
+      $.usages.MEMORY_MB: 1024
+
+- name: fail allocations over capacity
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+      $ENVIRON['CONSUMER_UUID']:
+          allocations:
+              $HISTORY['rp compute01'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 2049
+                      VCPU: 2
+          project_id: $ENVIRON['PROJECT_ID_ALT']
+          user_id: $ENVIRON['USER_ID_ALT']
+  status: 409
+  response_strings:
+      - The requested amount would exceed the capacity
+
+- name: fail allocations deep schema violate
+  desc: no schema yet
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  cow: moo
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+  status: 400
+
+- name: fail allocations shallow schema violate
+  desc: no schema yet
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          cow: moo
+  status: 400
+
+- name: fail resource provider not exist
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              # this rp does not exist
+              'c42def7b-498b-4442-9502-c7970b14bea4':
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+  status: 400
+  response_strings:
+      - that does not exist
+
+- name: fail resource class not in inventory
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+                      PCI_DEVICE: 1
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+  status: 409
+  response_strings:
+      - "Inventory for 'PCI_DEVICE' on"
+
+- name: fail resource class not exist
+  POST: /allocations
+  data:
+      $ENVIRON['INSTANCE_UUID']:
+          allocations:
+              $HISTORY['rp compute02'].$RESPONSE['uuid']:
+                  resources:
+                      MEMORY_MB: 1024
+                      VCPU: 2
+                      CUSTOM_PONY: 1
+              $HISTORY['rp storage01'].$RESPONSE['uuid']:
+                  resources:
+                      DISK_GB: 5
+          project_id: $ENVIRON['PROJECT_ID']
+          user_id: $ENVIRON['USER_ID']
+  status: 400
+  response_strings:
+      - No such resource class CUSTOM_PONY
diff --git a/nova/tests/functional/api/openstack/placement/gabbits/allocations.yaml b/nova/tests/functional/api/openstack/placement/gabbits/allocations.yaml
index bf9b64833202..403e9bbf7187 100644
--- a/nova/tests/functional/api/openstack/placement/gabbits/allocations.yaml
+++ b/nova/tests/functional/api/openstack/placement/gabbits/allocations.yaml
@@ -14,11 +14,11 @@ defaults:
 
 tests:
 
-- name: get allocations no consumer is 404
+- name: get allocations no consumer is 405
   GET: /allocations
-  status: 404
+  status: 405
   response_json_paths:
-     $.errors[0].title: Not Found
+     $.errors[0].title: Method Not Allowed
 
 - name: get allocations is empty dict
   GET: /allocations/599ffd2d-526a-4b2e-8683-f13ad25f9958
diff --git a/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml b/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml
index 6255f6833ccb..ccbdcbb8c9c6 100644
--- a/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml
+++ b/nova/tests/functional/api/openstack/placement/gabbits/microversion.yaml
@@ -39,13 +39,13 @@ tests:
   response_json_paths:
       $.errors[0].title: Not Acceptable
 
-- name: latest microversion is 1.12
+- name: latest microversion is 1.13
   GET: /
   request_headers:
       openstack-api-version: placement latest
   response_headers:
       vary: /OpenStack-API-Version/
-      openstack-api-version: placement 1.12
+      openstack-api-version: placement 1.13
 
 - name: other accept header bad version
   GET: /
diff --git a/nova/tests/unit/api/openstack/placement/test_microversion.py b/nova/tests/unit/api/openstack/placement/test_microversion.py
index fa103eb9257d..e5e38cd9885d 100644
--- a/nova/tests/unit/api/openstack/placement/test_microversion.py
+++ b/nova/tests/unit/api/openstack/placement/test_microversion.py
@@ -74,7 +74,7 @@ class TestMicroversionIntersection(test.NoDBTestCase):
     # if you add two different versions of method 'foobar' the
     # number only goes up by one if no other version foobar yet
     # exists. This operates as a simple sanity check.
-    TOTAL_VERSIONED_METHODS = 15
+    TOTAL_VERSIONED_METHODS = 16
 
     def test_methods_versioned(self):
         methods_data = microversion.VERSIONED_METHODS
diff --git a/placement-api-ref/source/allocations.inc b/placement-api-ref/source/allocations.inc
index e85f65d22ae2..8e3a0f9169b1 100644
--- a/placement-api-ref/source/allocations.inc
+++ b/placement-api-ref/source/allocations.inc
@@ -7,6 +7,51 @@ and used by some consumer of that resource. They indicate the amount
 of a particular resource that has been allocated to a given consumer
 of that resource from a particular resource provider.
 
+Manage allocations
+==================
+
+Create, update or delete allocations for multiple consumers in a single
+request. This allows a client to atomically set or swap allocations for
+multiple consumers as may be required during a migration or move type
+operation.
+
+The allocations for an individual consumer uuid mentioned in the request
+can be removed by setting the `allocations` to an empty object (see the
+example below).
+
+**Available as of microversion 1.13.**
+
+.. rest_method:: POST /allocations
+
+Normal response codes: 204
+
+Error response codes: badRequest(400), conflict(409)
+
+* `409 Conflict` if there is no available inventory in any of the
+  resource providers for any specified resource classes or inventories
+  are updated by another thread while attempting the operation.
+
+Request
+-------
+
+.. rest_parameters:: parameters.yaml
+
+  - consumer_uuid: consumer_uuid_body
+  - project_id: project_id_body
+  - user_id: user_id_body
+  - allocations: allocations_dict_empty
+  - resources: resources
+
+Request Example
+
+.. literalinclude:: manage-allocations-request.json
+   :language: javascript
+
+Response
+--------
+
+No body content is returned after a successful request
+
 List allocations
 ================
 
diff --git a/placement-api-ref/source/manage-allocations-request.json b/placement-api-ref/source/manage-allocations-request.json
new file mode 100644
index 000000000000..8bdcb2151d5d
--- /dev/null
+++ b/placement-api-ref/source/manage-allocations-request.json
@@ -0,0 +1,31 @@
+{
+  "30328d13-e299-4a93-a102-61e4ccabe474": {
+    "project_id": "131d4efb-abc0-4872-9b92-8c8b9dc4320f",
+    "user_id": "131d4efb-abc0-4872-9b92-8c8b9dc4320f",
+    "allocations": {
+      "e10927c4-8bc9-465d-ac60-d2f79f7e4a00": {
+        "resources": {
+          "VCPU": 2,
+          "MEMORY_MB": 3
+        }
+      }
+    }
+  },
+  "71921e4e-1629-4c5b-bf8d-338d915d2ef3": {
+    "project_id": "131d4efb-abc0-4872-9b92-8c8b9dc4320f",
+    "user_id": "131d4efb-abc0-4872-9b92-8c8b9dc4320f",
+    "allocations": {}
+  },
+  "48c1d40f-45d8-4947-8d46-52b4e1326df8": {
+    "project_id": "131d4efb-abc0-4872-9b92-8c8b9dc4320f",
+    "user_id": "131d4efb-abc0-4872-9b92-8c8b9dc4320f",
+    "allocations": {
+      "e10927c4-8bc9-465d-ac60-d2f79f7e4a00": {
+        "resources": {
+          "VCPU": 4,
+          "MEMORY_MB": 5
+        }
+      }
+    }
+  }
+}
diff --git a/placement-api-ref/source/parameters.yaml b/placement-api-ref/source/parameters.yaml
index e59f3a1cbcf8..5c000a701d8e 100644
--- a/placement-api-ref/source/parameters.yaml
+++ b/placement-api-ref/source/parameters.yaml
@@ -1,5 +1,5 @@
 # variables in path
-consumer_uuid:
+consumer_uuid: &consumer_uuid
   type: string
   in: path
   required: true
@@ -147,19 +147,29 @@ allocations_by_resource_provider:
   required: true
   description: >
     A dictionary of allocations keyed by resource provider uuid.
-allocations_dict:
+allocations_dict: &allocations_dict
   type: object
   in: body
   required: true
   min_version: 1.12
   description: >
     A dictionary of resource allocations keyed by resource provider uuid.
+allocations_dict_empty:
+  <<: *allocations_dict
+  description: >
+    A dictionary of resource allocations keyed by resource provider uuid.
+    If this is an empty object, allocations for this consumer will be
+    removed.
+  min_version: null
 capacity:
   type: integer
   in: body
   required: true
   description: >
     The amount of the resource that the provider can accommodate.
+consumer_uuid_body:
+  <<: *consumer_uuid
+  in: body
 inventories:
   type: object
   in: body
diff --git a/releasenotes/notes/post-allocations-427581fa41671820.yaml b/releasenotes/notes/post-allocations-427581fa41671820.yaml
new file mode 100644
index 000000000000..80a9115d4b6c
--- /dev/null
+++ b/releasenotes/notes/post-allocations-427581fa41671820.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Microversion 1.13 of the Placement API gives the ability to set or clear
+    allocations for more than one consumer uuid with a request to
+    ``POST /allocations``.