diff --git a/adjutant/actions/v1/base.py b/adjutant/actions/v1/base.py
index 4f6a4ec..e9341ee 100644
--- a/adjutant/actions/v1/base.py
+++ b/adjutant/actions/v1/base.py
@@ -19,6 +19,7 @@ from django.utils import timezone
 
 from adjutant.common.quota import QuotaManager
 from adjutant.common import user_store
+from adjutant.common.utils import str_datetime
 from adjutant.actions.models import Action
 
 
@@ -331,7 +332,7 @@ class UserMixin(ResourceMixin):
             user = id_manager.create_user(
                 name=self.username, password=password,
                 email=self.email, domain=self.domain_id,
-                created_on=str(timezone.now()))
+                created_on=str_datetime(timezone.now()))
         except Exception as e:
             # TODO: Narrow the Exceptions caught to a relevant set.
             self.add_note(
@@ -410,7 +411,7 @@ class ProjectMixin(ResourceMixin):
         description = getattr(self, "description", "")
         try:
             project = id_manager.create_project(
-                self.project_name, created_on=str(timezone.now()),
+                self.project_name, created_on=str_datetime(timezone.now()),
                 parent=self.parent_id, domain=self.domain_id,
                 description=description)
         except Exception as e:
diff --git a/adjutant/actions/v1/projects.py b/adjutant/actions/v1/projects.py
index de6a0a3..cbb6213 100644
--- a/adjutant/actions/v1/projects.py
+++ b/adjutant/actions/v1/projects.py
@@ -17,6 +17,7 @@ from uuid import uuid4
 from django.utils import timezone
 
 from adjutant.common import user_store
+from adjutant.common.utils import str_datetime
 from adjutant.actions.v1.base import (
     BaseAction, UserNameAction, UserMixin, ProjectMixin)
 
@@ -261,7 +262,7 @@ class NewProjectWithUserAction(UserNameAction, ProjectMixin, UserMixin):
                     user = id_manager.create_user(
                         name=self.username, password=password,
                         email=self.email, domain=self.domain_id,
-                        created_on=str(timezone.now()))
+                        created_on=str_datetime(timezone.now()))
                     self.set_cache('user_id', user.id)
                 else:
                     user = id_manager.get_user(user_id)
diff --git a/adjutant/common/constants.py b/adjutant/common/constants.py
new file mode 100644
index 0000000..528fa10
--- /dev/null
+++ b/adjutant/common/constants.py
@@ -0,0 +1,17 @@
+# Copyright (C) 2018 Catalyst IT Ltd
+#
+#    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.
+
+# Date formats to use when storing time data we expect to parse.
+DATE_FORMAT = "%Y-%m-%dT%H:%M:%S"
+DATE_FORMAT_MS = "%Y-%m-%dT%H:%M:%S.%f"
diff --git a/adjutant/common/utils.py b/adjutant/common/utils.py
new file mode 100644
index 0000000..a0b7ef2
--- /dev/null
+++ b/adjutant/common/utils.py
@@ -0,0 +1,24 @@
+# Copyright (C) 2018 Catalyst IT Ltd
+#
+#    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 datetime import datetime
+
+from adjutant.common import constants
+
+
+def str_datetime(datetime_obj, include_ms=False):
+    if include_ms:
+        return datetime.strftime(datetime_obj, constants.DATE_FORMAT_MS)
+    else:
+        return datetime.strftime(datetime_obj, constants.DATE_FORMAT)