diff --git a/app/main/views/service_settings.py b/app/main/views/service_settings.py
index 08591053b..c9e5740a0 100644
--- a/app/main/views/service_settings.py
+++ b/app/main/views/service_settings.py
@@ -397,11 +397,14 @@ def service_confirm_broadcast_account_type(service_id, account_type):
         abort(404)
 
     if form.validate_on_submit():
+        cached_service_user_ids = [user.id for user in current_service.active_users]
+
         service_api_client.set_service_broadcast_settings(
             current_service.id,
             service_mode=form.account_type.service_mode,
             broadcast_channel=form.account_type.broadcast_channel,
-            provider_restriction=form.account_type.provider_restriction
+            provider_restriction=form.account_type.provider_restriction,
+            cached_service_user_ids=cached_service_user_ids
         )
         create_broadcast_account_type_change_event(
             service_id=current_service.id,
diff --git a/app/notify_client/service_api_client.py b/app/notify_client/service_api_client.py
index 3be73ad38..f610700a9 100644
--- a/app/notify_client/service_api_client.py
+++ b/app/notify_client/service_api_client.py
@@ -618,13 +618,16 @@ class ServiceAPIClient(NotifyAdminAPIClient):
 
     @cache.delete('service-{service_id}')
     def set_service_broadcast_settings(
-        self, service_id, service_mode, broadcast_channel, provider_restriction
+        self, service_id, service_mode, broadcast_channel, provider_restriction, cached_service_user_ids
     ):
         """
         service_mode is one of "training" or "live"
-        broadcast channel is one of "test" or "severe"
+        broadcast channel is one of "operator", "test", "severe", "government"
         provider_restriction is one of "all", "three", "o2", "vodafone", "ee"
         """
+        if cached_service_user_ids:
+            redis_client.delete(*map('user-{}'.format, cached_service_user_ids))
+
         data = {
             "service_mode": service_mode,
             "broadcast_channel": broadcast_channel,
diff --git a/tests/app/main/views/test_service_settings.py b/tests/app/main/views/test_service_settings.py
index 9e96d77a1..7ad6cb6c6 100644
--- a/tests/app/main/views/test_service_settings.py
+++ b/tests/app/main/views/test_service_settings.py
@@ -5899,6 +5899,7 @@ def test_service_confirm_broadcast_account_type_posts_data_to_api_and_redirects(
     broadcast_channel,
     allowed_broadcast_provider,
     fake_uuid,
+    mock_get_users_by_service,
 ):
     set_service_broadcast_settings_mock = mocker.patch('app.service_api_client.set_service_broadcast_settings')
     mock_event_handler = mocker.patch('app.main.views.service_settings.create_broadcast_account_type_change_event')
@@ -5917,6 +5918,7 @@ def test_service_confirm_broadcast_account_type_posts_data_to_api_and_redirects(
         service_mode=service_mode,
         broadcast_channel=broadcast_channel,
         provider_restriction=allowed_broadcast_provider,
+        cached_service_user_ids=[fake_uuid]
     )
     mock_event_handler.assert_called_once_with(
         service_id=SERVICE_ONE_ID,
diff --git a/tests/app/notify_client/test_service_api_client.py b/tests/app/notify_client/test_service_api_client.py
index eae5a3ee5..6a058c1eb 100644
--- a/tests/app/notify_client/test_service_api_client.py
+++ b/tests/app/notify_client/test_service_api_client.py
@@ -404,7 +404,7 @@ def test_returns_value_from_cache(
     (service_api_client, 'delete_sms_sender', [SERVICE_ONE_ID, ''], {}),
     (service_api_client, 'update_service_callback_api', [SERVICE_ONE_ID] + [''] * 4, {}),
     (service_api_client, 'create_service_callback_api', [SERVICE_ONE_ID] + [''] * 3, {}),
-    (service_api_client, 'set_service_broadcast_settings', [SERVICE_ONE_ID, 'training', 'severe', None], {}),
+    (service_api_client, 'set_service_broadcast_settings', [SERVICE_ONE_ID, 'training', 'severe', 'all', []], {}),
     (user_api_client, 'add_user_to_service', [SERVICE_ONE_ID, uuid4(), [], []], {}),
     (invite_api_client, 'accept_invite', [SERVICE_ONE_ID, uuid4()], {}),
 ])
@@ -492,6 +492,23 @@ def test_deletes_cached_users_when_archiving_service(mocker, mock_get_service_te
     assert call(f'service-{SERVICE_ONE_ID}-template-*') in mock_redis_delete_by_pattern.call_args_list
 
 
+def test_deletes_cached_users_when_changing_broadcast_service_settings(mocker):
+    mock_redis_delete = mocker.patch('app.extensions.RedisClient.delete')
+
+    mocker.patch('notifications_python_client.base.BaseAPIClient.request', return_value={'data': ""})
+
+    service_api_client.set_service_broadcast_settings(SERVICE_ONE_ID,
+                                                      'live',
+                                                      'severe',
+                                                      'all',
+                                                      ["my-user-id1", "my-user-id2"])
+
+    assert mock_redis_delete.call_args_list == [
+        call('user-my-user-id1', 'user-my-user-id2'),
+        call(f'service-{SERVICE_ONE_ID}'),
+    ]
+
+
 def test_client_gets_guest_list(mocker):
     client = ServiceAPIClient()
     mock_get = mocker.patch.object(client, 'get', return_value=['a', 'b', 'c'])