diff --git a/app/utils.py b/app/utils.py
index e178c2dbb..752eadebc 100644
--- a/app/utils.py
+++ b/app/utils.py
@@ -680,5 +680,5 @@ def format_thousands(value):
 
 def is_less_than_90_days_ago(date_from_db):
     return (datetime.utcnow() - datetime.strptime(
-        date_from_db, '%a, %d %b %Y %X %Z'
+        date_from_db, "%Y-%m-%dT%H:%M:%S.%fZ"
     )).days < 90
diff --git a/tests/app/main/views/test_two_factor.py b/tests/app/main/views/test_two_factor.py
index 213066a5e..0eaff8489 100644
--- a/tests/app/main/views/test_two_factor.py
+++ b/tests/app/main/views/test_two_factor.py
@@ -49,7 +49,7 @@ def test_should_login_user_and_should_redirect_to_next_url(
         session['user_details'] = {
             'id': api_user_active['id'],
             'email': api_user_active['email_address']}
-    api_user_active['email_access_validated_at'] = 'Sun, 23 Jan 2020 11:28:25 GMT'
+    api_user_active['email_access_validated_at'] = '2020-01-23T11:35:21.726132Z'
 
     response = client.post(url_for('main.two_factor', next='/services/{}'.format(SERVICE_ONE_ID)),
                            data={'sms_code': '12345'})
@@ -72,7 +72,7 @@ def test_should_send_email_and_redirect_to_info_page_if_user_needs_to_revalidate
     mocker
 ):
     mocker.patch('app.user_api_client.get_user', return_value=api_user_active)
-    api_user_active['email_access_validated_at'] = 'Sun, 03 Mar 2019 11:28:25 GMT'
+    api_user_active['email_access_validated_at'] = '2019-03-23T11:35:21.726132Z'
     with client.session_transaction() as session:
         session['user_details'] = {
             'id': api_user_active['id'],
@@ -99,7 +99,7 @@ def test_should_login_user_and_not_redirect_to_external_url(
         session['user_details'] = {
             'id': api_user_active['id'],
             'email': api_user_active['email_address']}
-    api_user_active['email_access_validated_at'] = 'Sun, 23 Jan 2020 11:28:25 GMT'
+    api_user_active['email_access_validated_at'] = '2020-01-23T11:35:21.726132Z'
 
     response = client.post(url_for('main.two_factor', next='http://www.google.com'),
                            data={'sms_code': '12345'})
@@ -120,7 +120,7 @@ def test_should_login_user_and_redirect_to_show_accounts(
         session['user_details'] = {
             'id': api_user_active['id'],
             'email': api_user_active['email_address']}
-    api_user_active['email_access_validated_at'] = 'Sun, 23 Jan 2020 11:28:25 GMT'
+    api_user_active['email_access_validated_at'] = '2020-01-23T11:35:21.726132Z'
 
     response = client.post(url_for('main.two_factor'),
                            data={'sms_code': '12345'})
@@ -162,7 +162,7 @@ def test_should_login_user_when_multiple_valid_codes_exist(
         session['user_details'] = {
             'id': api_user_active['id'],
             'email': api_user_active['email_address']}
-    api_user_active['email_access_validated_at'] = 'Sun, 23 Jan 2020 11:28:25 GMT'
+    api_user_active['email_access_validated_at'] = '2020-01-23T11:35:21.726132Z'
 
     response = client.post(url_for('main.two_factor'),
                            data={'sms_code': '23456'})
@@ -184,7 +184,7 @@ def test_two_factor_should_set_password_when_new_password_exists_in_session(
             'id': api_user_active['id'],
             'email': api_user_active['email_address'],
             'password': 'changedpassword'}
-    api_user_active['email_access_validated_at'] = 'Sun, 23 Jan 2020 11:28:25 GMT'
+    api_user_active['email_access_validated_at'] = '2020-01-23T11:35:21.726132Z'
 
     response = client.post(url_for('main.two_factor'),
                            data={'sms_code': '12345'})
@@ -234,7 +234,7 @@ def test_two_factor_should_activate_pending_user(
 ):
     mocker.patch('app.user_api_client.get_user', return_value=api_user_pending)
     mocker.patch('app.service_api_client.get_services', return_value={'data': []})
-    api_user_pending['email_access_validated_at'] = 'Sun, 23 Jan 2020 11:28:25 GMT'
+    api_user_pending['email_access_validated_at'] = '2020-01-23T11:35:21.726132Z'
     with client.session_transaction() as session:
         session['user_details'] = {
             'id': api_user_pending['id'],
diff --git a/tests/app/test_utils.py b/tests/app/test_utils.py
index ce87009cc..fd0b991f3 100644
--- a/tests/app/test_utils.py
+++ b/tests/app/test_utils.py
@@ -510,8 +510,8 @@ def test_get_letter_validation_error_for_known_errors(
 
 
 @pytest.mark.parametrize("date_from_db, expected_result", [
-    ('Sun, 17 Nov 2019 11:28:25 GMT', True),
-    ('Sun, 16 Nov 2019 11:28:25 GMT', False),
+    ('2019-11-17T11:35:21.726132Z', True),
+    ('2019-11-16T11:35:21.726132Z', False),
 ])
 @freeze_time('2020-02-14T12:00:00')
 def test_is_less_than_90_days_ago(date_from_db, expected_result):