diff --git a/app/celery/scheduled_tasks.py b/app/celery/scheduled_tasks.py
index 82ce46cb4..ea299307a 100644
--- a/app/celery/scheduled_tasks.py
+++ b/app/celery/scheduled_tasks.py
@@ -4,7 +4,7 @@ from flask import current_app
 from sqlalchemy import between
 from sqlalchemy.exc import SQLAlchemyError
 
-from app import notify_celery, zendesk_client
+from app import db, notify_celery, zendesk_client
 from app.celery.broadcast_message_tasks import trigger_link_test
 from app.celery.letters_pdf_tasks import get_pdf_for_templated_letter
 from app.celery.tasks import (
@@ -48,6 +48,8 @@ from app.models import (
     JOB_STATUS_IN_PROGRESS,
     JOB_STATUS_PENDING,
     SMS_TYPE,
+    BroadcastMessage,
+    BroadcastStatusType,
     Job,
 )
 from app.notifications.process_notifications import send_notification_to_queue
@@ -304,3 +306,16 @@ def trigger_link_tests():
     if current_app.config['CBC_PROXY_ENABLED']:
         for cbc_name in current_app.config['ENABLED_CBCS']:
             trigger_link_test.apply_async(kwargs={'provider': cbc_name}, queue=QueueNames.BROADCASTS)
+
+
+@notify_celery.task(name='auto-expire-broadcast-messages')
+def auto_expire_broadcast_messages():
+    expired_broadcasts = BroadcastMessage.query.filter(
+        BroadcastMessage.finishes_at <= datetime.now(),
+        BroadcastMessage.status == BroadcastStatusType.BROADCASTING,
+    )
+
+    for broadcast in expired_broadcasts:
+        broadcast.status = BroadcastStatusType.COMPLETED
+
+    db.session.commit()
diff --git a/app/config.py b/app/config.py
index 043d82eb8..973eb3e28 100644
--- a/app/config.py
+++ b/app/config.py
@@ -323,6 +323,11 @@ class Config(object):
             'schedule': timedelta(minutes=15),
             'options': {'queue': QueueNames.PERIODIC}
         },
+        'auto-expire-broadcast-messages': {
+            'task': 'auto-expire-broadcast-messages',
+            'schedule': timedelta(minutes=5),
+            'options': {'queue': QueueNames.PERIODIC}
+        },
     }
     CELERY_QUEUES = []
 
diff --git a/tests/app/celery/test_scheduled_tasks.py b/tests/app/celery/test_scheduled_tasks.py
index d72e6d544..06dde61a3 100644
--- a/tests/app/celery/test_scheduled_tasks.py
+++ b/tests/app/celery/test_scheduled_tasks.py
@@ -8,6 +8,7 @@ from freezegun import freeze_time
 
 from app.celery import scheduled_tasks
 from app.celery.scheduled_tasks import (
+    auto_expire_broadcast_messages,
     check_for_missing_rows_in_completed_jobs,
     check_for_services_with_high_failure_rates_or_sending_to_tv_numbers,
     check_if_letters_still_in_created,
@@ -30,9 +31,15 @@ from app.models import (
     JOB_STATUS_PENDING,
     NOTIFICATION_DELIVERED,
     NOTIFICATION_PENDING_VIRUS_CHECK,
+    BroadcastStatusType,
 )
 from tests.app import load_example_csv
-from tests.app.db import create_job, create_notification, create_template
+from tests.app.db import (
+    create_broadcast_message,
+    create_job,
+    create_notification,
+    create_template,
+)
 from tests.conftest import set_config
 
 
@@ -624,3 +631,27 @@ def test_trigger_link_does_nothing_if_cbc_proxy_disabled(
         trigger_link_tests()
 
     assert mock_trigger_link_test.called is False
+
+
+@freeze_time('2021-07-19 15:50')
+@pytest.mark.parametrize('status, finishes_at, final_status', [
+    (BroadcastStatusType.BROADCASTING, '2021-07-19 16:00', BroadcastStatusType.BROADCASTING),
+    (BroadcastStatusType.BROADCASTING, '2021-07-19 15:40', BroadcastStatusType.COMPLETED),
+    (BroadcastStatusType.BROADCASTING, None, BroadcastStatusType.BROADCASTING),
+    (BroadcastStatusType.PENDING_APPROVAL, None, BroadcastStatusType.PENDING_APPROVAL),
+    (BroadcastStatusType.CANCELLED, '2021-07-19 15:40', BroadcastStatusType.CANCELLED),
+])
+def test_auto_expire_broadcast_messages(
+    status,
+    finishes_at,
+    final_status,
+    sample_template
+):
+    message = create_broadcast_message(
+        status=status,
+        finishes_at=finishes_at,
+        template=sample_template,
+    )
+
+    auto_expire_broadcast_messages()
+    assert message.status == final_status