diff --git a/app/dao/jobs_dao.py b/app/dao/jobs_dao.py
index ce09fef7b..cee3d16b1 100644
--- a/app/dao/jobs_dao.py
+++ b/app/dao/jobs_dao.py
@@ -209,9 +209,9 @@ def can_letter_job_be_cancelled(job):
 
 
 def find_jobs_with_missing_rows():
-    # Jobs can be a maximum of 50,000 rows. It typically takes 5 minutes to create all those notifications.
-    # Using 10 minutes as a condition seems reasonable.
-    ten_minutes_ago = datetime.utcnow() - timedelta(minutes=10)
+    # Jobs can be a maximum of 100,000 rows. It typically takes 10 minutes to create all those notifications.
+    # Using 20 minutes as a condition seems reasonable.
+    ten_minutes_ago = datetime.utcnow() - timedelta(minutes=20)
     yesterday = datetime.utcnow() - timedelta(days=1)
     jobs_with_rows_missing = db.session.query(
         func.count(Notification.id).label('actual_count'),
diff --git a/tests/app/celery/test_scheduled_tasks.py b/tests/app/celery/test_scheduled_tasks.py
index 655d6e699..c29ea1637 100644
--- a/tests/app/celery/test_scheduled_tasks.py
+++ b/tests/app/celery/test_scheduled_tasks.py
@@ -398,6 +398,36 @@ def test_check_templated_letter_state_during_utc(mocker, sample_letter_template)
     )
 
 
+@pytest.mark.parametrize('offset', (
+    timedelta(days=1),
+    pytest.param(timedelta(hours=23, minutes=59), marks=pytest.mark.xfail),
+    pytest.param(timedelta(minutes=20), marks=pytest.mark.xfail),
+    timedelta(minutes=19),
+))
+def test_check_for_missing_rows_in_completed_jobs_ignores_old_and_new_jobs(
+    mocker,
+    sample_email_template,
+    offset,
+):
+    mocker.patch('app.celery.tasks.s3.get_job_and_metadata_from_s3',
+                 return_value=(load_example_csv('multiple_email'), {"sender_id": None}))
+    mocker.patch('app.encryption.encrypt', return_value="something_encrypted")
+    process_row = mocker.patch('app.celery.scheduled_tasks.process_row')
+
+    job = create_job(
+        template=sample_email_template,
+        notification_count=5,
+        job_status=JOB_STATUS_FINISHED,
+        processing_finished=datetime.utcnow() - offset,
+    )
+    for i in range(0, 4):
+        create_notification(job=job, job_row_number=i)
+
+    check_for_missing_rows_in_completed_jobs()
+
+    assert process_row.called is False
+
+
 def test_check_for_missing_rows_in_completed_jobs(mocker, sample_email_template):
     mocker.patch('app.celery.tasks.s3.get_job_and_metadata_from_s3',
                  return_value=(load_example_csv('multiple_email'), {"sender_id": None}))
@@ -407,7 +437,7 @@ def test_check_for_missing_rows_in_completed_jobs(mocker, sample_email_template)
     job = create_job(template=sample_email_template,
                      notification_count=5,
                      job_status=JOB_STATUS_FINISHED,
-                     processing_finished=datetime.utcnow() - timedelta(minutes=11))
+                     processing_finished=datetime.utcnow() - timedelta(minutes=20))
     for i in range(0, 4):
         create_notification(job=job, job_row_number=i)
 
@@ -428,7 +458,7 @@ def test_check_for_missing_rows_in_completed_jobs_calls_save_email(mocker, sampl
     job = create_job(template=sample_email_template,
                      notification_count=5,
                      job_status=JOB_STATUS_FINISHED,
-                     processing_finished=datetime.utcnow() - timedelta(minutes=11))
+                     processing_finished=datetime.utcnow() - timedelta(minutes=20))
     for i in range(0, 4):
         create_notification(job=job, job_row_number=i)
 
@@ -452,7 +482,7 @@ def test_check_for_missing_rows_in_completed_jobs_uses_sender_id(mocker, sample_
     job = create_job(template=sample_email_template,
                      notification_count=5,
                      job_status=JOB_STATUS_FINISHED,
-                     processing_finished=datetime.utcnow() - timedelta(minutes=11))
+                     processing_finished=datetime.utcnow() - timedelta(minutes=20))
     for i in range(0, 4):
         create_notification(job=job, job_row_number=i)
 
diff --git a/tests/app/dao/test_jobs_dao.py b/tests/app/dao/test_jobs_dao.py
index fccb9b96c..181194010 100644
--- a/tests/app/dao/test_jobs_dao.py
+++ b/tests/app/dao/test_jobs_dao.py
@@ -446,14 +446,14 @@ def test_find_jobs_with_missing_rows(sample_email_template):
     healthy_job = create_job(template=sample_email_template,
                              notification_count=3,
                              job_status=JOB_STATUS_FINISHED,
-                             processing_finished=datetime.utcnow() - timedelta(minutes=11)
+                             processing_finished=datetime.utcnow() - timedelta(minutes=20)
                              )
     for i in range(0, 3):
         create_notification(job=healthy_job, job_row_number=i)
     job_with_missing_rows = create_job(template=sample_email_template,
                                        notification_count=5,
                                        job_status=JOB_STATUS_FINISHED,
-                                       processing_finished=datetime.utcnow() - timedelta(minutes=11)
+                                       processing_finished=datetime.utcnow() - timedelta(minutes=20)
                                        )
     for i in range(0, 4):
         create_notification(job=job_with_missing_rows, job_row_number=i)