diff --git a/cms/djangoapps/contentstore/management/commands/backfill_course_tabs.py b/cms/djangoapps/contentstore/management/commands/backfill_course_tabs.py
new file mode 100644
index 0000000000..b163c573e5
--- /dev/null
+++ b/cms/djangoapps/contentstore/management/commands/backfill_course_tabs.py
@@ -0,0 +1,53 @@
+"""
+Management command to backfill default course tabs for all courses. This command is essentially for
+when a new default tab is added and we need to update all existing courses. Any new courses will pick
+up the new tab automatically via course creation and the CourseTabList.initialize_default method.
+People updating to Nutmeg release should run this command as part of the upgrade process.
+
+This should be invoked from the Studio process.
+"""
+import logging
+
+from django.core.management.base import BaseCommand
+
+from xmodule.tabs import CourseTabList
+from xmodule.modulestore import ModuleStoreEnum
+from xmodule.modulestore.django import modulestore
+
+logger = logging.getLogger(__name__)
+
+
+class Command(BaseCommand):
+    """
+    Invoke with:
+        python manage.py cms backfill_course_tabs
+    """
+    help = (
+        'Backfill default course tabs for all courses. This command is essentially for when a new default '
+        'tab is added and we need to update all existing courses. Any new courses will pick up the new '
+        'tab automatically via course creation and the CourseTabList.initialize_default method.'
+    )
+
+    def handle(self, *args, **options):
+        """
+        Gathers all course keys in the modulestore and updates the course tabs
+        if there are any new default course tabs. Else, makes no updates.
+        """
+        store = modulestore()
+        course_keys = sorted(
+            (course.id for course in store.get_course_summaries()),
+            key=str  # Different types of CourseKeys can't be compared without this.
+        )
+        logger.info(f'{len(course_keys)} courses read from modulestore.')
+
+        for course_key in course_keys:
+            course = store.get_course(course_key, depth=1)
+            existing_tabs = {tab.type for tab in course.tabs}
+            CourseTabList.initialize_default(course)
+            new_tabs = {tab.type for tab in course.tabs}
+
+            if existing_tabs != new_tabs:
+                # This will trigger the Course Published Signal which is necessary to update
+                # the corresponding Course Overview
+                logger.info(f'Updating tabs for {course_key}.')
+                store.update_item(course, ModuleStoreEnum.UserID.mgmt_command)
diff --git a/cms/djangoapps/contentstore/management/commands/tests/test_backfill_course_tabs.py b/cms/djangoapps/contentstore/management/commands/tests/test_backfill_course_tabs.py
new file mode 100644
index 0000000000..d63979d2fe
--- /dev/null
+++ b/cms/djangoapps/contentstore/management/commands/tests/test_backfill_course_tabs.py
@@ -0,0 +1,131 @@
+"""
+Tests for `backfill_course_outlines` Studio (cms) management command.
+"""
+from unittest import mock
+
+from django.core.management import call_command
+
+from xmodule.modulestore import ModuleStoreEnum
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory
+from xmodule.tabs import InvalidTabsException
+
+
+class BackfillCourseTabsTest(ModuleStoreTestCase):
+    """
+    Test `backfill_course_tabs`
+    """
+    @mock.patch('cms.djangoapps.contentstore.management.commands.backfill_course_tabs.logger')
+    def test_no_tabs_to_add(self, mock_logger):
+        """ Calls command with a course already having all default tabs. """
+        course = CourseFactory()
+        tabs_before = course.tabs
+
+        call_command('backfill_course_tabs')
+
+        course = self.store.get_course(course.id)
+        tabs_after = course.tabs
+        assert tabs_before == tabs_after
+        # Ensure update_item was never called since there were no changes necessary
+        # Using logger as a proxy. First time is number of courses read.
+        assert mock_logger.info.call_count == 1
+
+    @mock.patch('cms.djangoapps.contentstore.management.commands.backfill_course_tabs.logger')
+    def test_add_one_tab(self, mock_logger):
+        """
+        Calls command on a course with existing tabs, but not all default ones.
+        """
+        course = CourseFactory()
+        course.tabs = [tab for tab in course.tabs if tab.type != 'dates']
+        self.update_course(course, ModuleStoreEnum.UserID.test)
+        assert len(course.tabs) == 6
+        assert 'dates' not in {tab.type for tab in course.tabs}
+
+        call_command('backfill_course_tabs')
+
+        course = self.store.get_course(course.id)
+        assert len(course.tabs) == 7
+        assert 'dates' in {tab.type for tab in course.tabs}
+        mock_logger.info.assert_called_with(f'Updating tabs for {course.id}.')
+        assert mock_logger.info.call_count == 2
+
+        call_command('backfill_course_tabs')
+        # Ensure rerunning the command does not require another update on the course.
+        # Goes up by one from the courses read log.
+        assert mock_logger.info.call_count == 3
+
+    @mock.patch('cms.djangoapps.contentstore.management.commands.backfill_course_tabs.logger')
+    def test_multiple_courses_one_update(self, mock_logger):
+        """
+        Calls command on multiple courses, some that already have all their tabs, and some that need updates.
+        """
+        CourseFactory()
+        CourseFactory()
+        CourseFactory()
+        course = CourseFactory()
+        course.tabs = [tab for tab in course.tabs if tab.type in ('course_info', 'courseware')]
+        self.update_course(course, ModuleStoreEnum.UserID.test)
+        assert len(course.tabs) == 2
+        assert 'dates' not in {tab.type for tab in course.tabs}
+        assert 'progress' not in {tab.type for tab in course.tabs}
+
+        call_command('backfill_course_tabs')
+
+        course = self.store.get_course(course.id)
+        assert len(course.tabs) == 7
+        assert 'dates' in {tab.type for tab in course.tabs}
+        assert 'progress' in {tab.type for tab in course.tabs}
+        mock_logger.info.assert_any_call('4 courses read from modulestore.')
+        mock_logger.info.assert_called_with(f'Updating tabs for {course.id}.')
+        assert mock_logger.info.call_count == 2
+
+        call_command('backfill_course_tabs')
+        # Ensure rerunning the command does not require another update on the course.
+        # Goes up by one from the courses read log.
+        assert mock_logger.info.call_count == 3
+
+    @mock.patch('cms.djangoapps.contentstore.management.commands.backfill_course_tabs.logger')
+    def test_multiple_courses_all_updated(self, mock_logger):
+        """
+        Calls command on multiple courses where all of them need updates.
+        """
+        course_1 = CourseFactory()
+        course_1.tabs = [tab for tab in course_1.tabs if tab.type != 'dates']
+        self.update_course(course_1, ModuleStoreEnum.UserID.test)
+        course_2 = CourseFactory()
+        course_2.tabs = [tab for tab in course_2.tabs if tab.type != 'progress']
+        self.update_course(course_2, ModuleStoreEnum.UserID.test)
+        assert len(course_1.tabs) == 6
+        assert len(course_2.tabs) == 6
+        assert 'dates' not in {tab.type for tab in course_1.tabs}
+        assert 'progress' not in {tab.type for tab in course_2.tabs}
+
+        call_command('backfill_course_tabs')
+
+        course_1 = self.store.get_course(course_1.id)
+        course_2 = self.store.get_course(course_2.id)
+        assert len(course_1.tabs) == 7
+        assert len(course_2.tabs) == 7
+        assert 'dates' in {tab.type for tab in course_1.tabs}
+        assert 'progress' in {tab.type for tab in course_2.tabs}
+        mock_logger.info.assert_any_call('2 courses read from modulestore.')
+        mock_logger.info.assert_any_call(f'Updating tabs for {course_1.id}.')
+        mock_logger.info.assert_any_call(f'Updating tabs for {course_2.id}.')
+        assert mock_logger.info.call_count == 3
+
+        call_command('backfill_course_tabs')
+        # Ensure rerunning the command does not require another update on any courses.
+        # Goes up by one from the courses read log.
+        assert mock_logger.info.call_count == 4
+
+    @mock.patch('cms.djangoapps.contentstore.management.commands.backfill_course_tabs.logger')
+    def test_command_fails_if_error_raised(self, mock_logger):
+        CourseFactory()
+        with mock.patch(
+            'cms.djangoapps.contentstore.management.commands.backfill_course_tabs.CourseTabList.initialize_default',
+            side_effect=InvalidTabsException
+        ):
+            with self.assertRaises(InvalidTabsException):
+                call_command('backfill_course_tabs')
+        # Never calls the update, but does make it through grabbing the courses
+        mock_logger.info.assert_called_once_with('1 courses read from modulestore.')
diff --git a/cms/djangoapps/contentstore/tasks.py b/cms/djangoapps/contentstore/tasks.py
index f4c9c5d0d4..20146caf1f 100644
--- a/cms/djangoapps/contentstore/tasks.py
+++ b/cms/djangoapps/contentstore/tasks.py
@@ -5,10 +5,10 @@ This file contains celery tasks for contentstore views
 import base64
 import json
 import os
-import shutil  # lint-amnesty, pylint: disable=wrong-import-order
-import tarfile  # lint-amnesty, pylint: disable=wrong-import-order
-from datetime import datetime  # lint-amnesty, pylint: disable=wrong-import-order
-from tempfile import NamedTemporaryFile, mkdtemp  # lint-amnesty, pylint: disable=wrong-import-order
+import shutil
+import tarfile
+from datetime import datetime
+from tempfile import NamedTemporaryFile, mkdtemp
 
 import olxcleaner
 import pkg_resources
@@ -17,7 +17,6 @@ from celery import shared_task
 from celery.utils.log import get_task_logger
 from django.conf import settings
 from django.contrib.auth import get_user_model
-from django.contrib.auth.models import User  # lint-amnesty, pylint: disable=imported-auth-user
 from django.core.exceptions import SuspiciousOperation
 from django.core.files import File
 from django.test import RequestFactory
diff --git a/cms/djangoapps/contentstore/views/tests/test_tabs.py b/cms/djangoapps/contentstore/views/tests/test_tabs.py
index fae6ee1f7f..e366420d22 100644
--- a/cms/djangoapps/contentstore/views/tests/test_tabs.py
+++ b/cms/djangoapps/contentstore/views/tests/test_tabs.py
@@ -193,11 +193,12 @@ class PrimitiveTabEdit(ModuleStoreTestCase):
             tabs.primitive_delete(course, 1)
         with self.assertRaises(IndexError):
             tabs.primitive_delete(course, 7)
-        assert course.tabs[2] != {'type': 'discussion', 'name': 'Discussion'}
+
+        assert course.tabs[2] != {'type': 'dates', 'name': 'Dates'}
         tabs.primitive_delete(course, 2)
         assert {'type': 'progress'} not in course.tabs
-        # Check that discussion has shifted up
-        assert course.tabs[2] == {'type': 'discussion', 'name': 'Discussion'}
+        # Check that dates has shifted up
+        assert course.tabs[2] == {'type': 'dates', 'name': 'Dates'}
 
     def test_insert(self):
         """Test primitive tab insertion."""
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_cross_modulestore_import_export.py b/common/lib/xmodule/xmodule/modulestore/tests/test_cross_modulestore_import_export.py
index 365bc8cace..21d9ddccd5 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_cross_modulestore_import_export.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_cross_modulestore_import_export.py
@@ -30,7 +30,6 @@ from xmodule.modulestore.tests.utils import (
     SPLIT_MODULESTORE_SETUP,
     TEST_DATA_DIR,
     MongoContentstoreBuilder,
-    mock_tab_from_json
 )
 from xmodule.modulestore.xml_exporter import export_course_to_xml
 from xmodule.modulestore.xml_importer import import_course_from_xml
@@ -61,7 +60,6 @@ class CrossStoreXMLRoundtrip(CourseComparisonTest, PartitionTestCase):
         self.addCleanup(rmtree, self.export_dir, ignore_errors=True)
 
     @patch('xmodule.video_module.video_module.edxval_api', None)
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
     @ddt.data(*itertools.product(
         MODULESTORE_SETUPS,
         MODULESTORE_SETUPS,
@@ -72,7 +70,7 @@ class CrossStoreXMLRoundtrip(CourseComparisonTest, PartitionTestCase):
     @ddt.unpack
     def test_round_trip(
             self, source_builder, dest_builder, source_content_builder,
-            dest_content_builder, course_data_name, _mock_tab_from_json
+            dest_content_builder, course_data_name,
     ):
         # Construct the contentstore for storing the first import
         with source_content_builder.build() as source_content:
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py b/common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py
index 8d1fc06e29..5d50dfb5ad 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py
@@ -50,11 +50,7 @@ from xmodule.modulestore.store_utilities import DETACHED_XBLOCK_TYPES
 from xmodule.modulestore.tests.factories import check_exact_number_of_calls, check_mongo_calls, mongo_uses_error_check
 from xmodule.modulestore.tests.mongo_connection import MONGO_HOST, MONGO_PORT_NUM
 from xmodule.modulestore.tests.test_asides import AsideTestType
-from xmodule.modulestore.tests.utils import (
-    MongoContentstoreBuilder,
-    create_modulestore_instance,
-    mock_tab_from_json
-)
+from xmodule.modulestore.tests.utils import MongoContentstoreBuilder, create_modulestore_instance
 from xmodule.modulestore.xml_exporter import export_course_to_xml
 from xmodule.modulestore.xml_importer import LocationMixin, import_course_from_xml
 from xmodule.tests import DATA_DIR, CourseComparisonTest
@@ -2659,9 +2655,8 @@ class TestMixedModuleStore(CommonMixedModuleStoreSetup):
                 self.store.clone_course(course_key, dest_course_id, self.user_id)
                 signal_handler.send.assert_called_with('course_published', course_key=dest_course_id)
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
     @ddt.data(ModuleStoreEnum.Type.mongo, ModuleStoreEnum.Type.split)
-    def test_course_publish_signal_import_firing(self, default, _from_json):
+    def test_course_publish_signal_import_firing(self, default):
         with MongoContentstoreBuilder().build() as contentstore:
             signal_handler = Mock(name='signal_handler')
             self.store = MixedModuleStore(
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_mongo.py b/common/lib/xmodule/xmodule/modulestore/tests/test_mongo.py
index f4bbbfdbb1..cc2cca9c1b 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_mongo.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_mongo.py
@@ -35,7 +35,6 @@ from xmodule.modulestore.inheritance import InheritanceMixin
 from xmodule.modulestore.mongo import MongoKeyValueStore
 from xmodule.modulestore.mongo.base import as_draft
 from xmodule.modulestore.tests.mongo_connection import MONGO_HOST, MONGO_PORT_NUM
-from xmodule.modulestore.tests.utils import mock_tab_from_json
 from xmodule.modulestore.xml_exporter import export_course_to_xml
 from xmodule.modulestore.xml_importer import LocationMixin, import_course_from_xml, perform_xlint
 from xmodule.tests import DATA_DIR
@@ -131,37 +130,46 @@ class TestMongoModuleStoreBase(TestCase):
 
         )
 
-        with patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json):
-            import_course_from_xml(
-                draft_store,
-                999,
-                DATA_DIR,
-                cls.courses,
-                static_content_store=content_store
-            )
+        import_course_from_xml(
+            draft_store,
+            999,
+            DATA_DIR,
+            cls.courses,
+            static_content_store=content_store
+        )
 
-            # also test a course with no importing of static content
-            import_course_from_xml(
-                draft_store,
-                999,
-                DATA_DIR,
-                ['test_import_course'],
-                static_content_store=content_store,
-                do_import_static=False,
-                verbose=True
-            )
+        # also test a course with no importing of static content
+        import_course_from_xml(
+            draft_store,
+            999,
+            DATA_DIR,
+            ['test_import_course'],
+            static_content_store=content_store,
+            do_import_static=False,
+            verbose=True
+        )
 
-            # also import a course under a different course_id (especially ORG)
-            import_course_from_xml(
-                draft_store,
-                999,
-                DATA_DIR,
-                ['test_import_course'],
-                static_content_store=content_store,
-                do_import_static=False,
-                verbose=True,
-                target_id=CourseKey.from_string('guestx/foo/bar')
-            )
+        # also import a course under a different course_id (especially ORG)
+        import_course_from_xml(
+            draft_store,
+            999,
+            DATA_DIR,
+            ['test_import_course'],
+            static_content_store=content_store,
+            do_import_static=False,
+            verbose=True,
+            target_id=CourseKey.from_string('guestx/foo/bar')
+        )
+
+        # Import a course for `test_reference_converters` since it manipulates the saved course
+        # which can cause any other test using the same course to have a flakey error
+        import_course_from_xml(
+            draft_store,
+            999,
+            DATA_DIR,
+            ['test_import_course_2'],
+            static_content_store=content_store
+        )
 
         return content_store, draft_store
 
@@ -206,12 +214,11 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
         )
         assert store.get_modulestore_type('') == ModuleStoreEnum.Type.mongo
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_courses(self, _from_json):
+    def test_get_courses(self):
         '''Make sure the course objects loaded properly'''
         courses = self.draft_store.get_courses()
 
-        assert len(courses) == 6
+        assert len(courses) == 7
         course_ids = [course.id for course in courses]
 
         for course_key in [
@@ -224,6 +231,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
                 ['edX', 'test_unicode', '2012_Fall'],
                 ['edX', 'toy', '2012_Fall'],
                 ['guestx', 'foo', 'bar'],
+                ['edX', 'test_import', '2014_Fall'],
             ]
         ]:
             assert course_key in course_ids
@@ -236,8 +244,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
             assert not self.draft_store.has_course(mix_cased)
             assert self.draft_store.has_course(mix_cased, ignore_case=True)
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_org_courses(self, _from_json):
+    def test_get_org_courses(self):
         """
         Make sure that we can query for a filtered list of courses for a given ORG
         """
@@ -255,7 +262,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
             assert course_key in course_ids
 
         courses = self.draft_store.get_courses(org='edX')
-        assert len(courses) == 5
+        assert len(courses) == 6
         course_ids = [course.id for course in courses]
 
         for course_key in [
@@ -266,6 +273,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
                 ['edX', 'test_import_course', '2012_Fall'],
                 ['edX', 'test_unicode', '2012_Fall'],
                 ['edX', 'toy', '2012_Fall'],
+                ['edX', 'test_import', '2014_Fall'],
             ]
         ]:
             assert course_key in course_ids
@@ -431,8 +439,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
                 {'displayname': 'hello'}
             )
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_courses_for_wiki(self, _from_json):
+    def test_get_courses_for_wiki(self):
         """
         Test the get_courses_for_wiki method
         """
@@ -473,7 +480,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
         """
         Test that references types get deserialized correctly
         """
-        course_key = CourseKey.from_string('edX/toy/2012_Fall')
+        course_key = CourseKey.from_string('edX/test_import/2014_Fall')
 
         def setup_test():
             course = self.draft_store.get_course(course_key)
@@ -548,8 +555,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
         check_mongo_fields()
 
     @patch('xmodule.video_module.video_module.edxval_api', None)
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_export_course_image(self, _from_json):
+    def test_export_course_image(self):
         """
         Test to make sure that we have a course image in the contentstore,
         then export it to ensure it gets copied to both file locations.
@@ -567,8 +573,7 @@ class TestMongoModuleStore(TestMongoModuleStoreBase):
         assert path(root_dir / 'test_export/static/images_course_image.jpg').isfile()
 
     @patch('xmodule.video_module.video_module.edxval_api', None)
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_export_course_image_nondefault(self, _from_json):
+    def test_export_course_image_nondefault(self):
         """
         Make sure that if a non-default image path is specified that we
         don't export it to the static default location
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_split_modulestore.py b/common/lib/xmodule/xmodule/modulestore/tests/test_split_modulestore.py
index 3550ef69ea..55623b217e 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_split_modulestore.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_split_modulestore.py
@@ -39,7 +39,7 @@ from xmodule.modulestore.split_mongo.split import SplitMongoModuleStore
 from xmodule.modulestore.tests.factories import check_mongo_calls
 from xmodule.modulestore.tests.mongo_connection import MONGO_HOST, MONGO_PORT_NUM
 from xmodule.modulestore.tests.test_modulestore import check_has_course_method
-from xmodule.modulestore.tests.utils import mock_tab_from_json
+from xmodule.tabs import CourseTab
 from xmodule.x_module import XModuleMixin
 
 BRANCH_NAME_DRAFT = ModuleStoreEnum.BranchName.draft
@@ -96,21 +96,10 @@ class SplitModuleTest(unittest.TestCase):
             "user_id": TEST_USER_ID,
             "fields": {
                 "tabs": [
-                    {
-                        "type": "courseware"
-                    },
-                    {
-                        "type": "course_info",
-                        "name": "Course Info"
-                    },
-                    {
-                        "type": "discussion",
-                        "name": "Discussion"
-                    },
-                    {
-                        "type": "wiki",
-                        "name": "Wiki"
-                    }
+                    CourseTab.load('courseware'),
+                    CourseTab.load('course_info'),
+                    CourseTab.load('discussion'),
+                    CourseTab.load('wiki'),
                 ],
                 "start": _date_field.from_json("2013-02-14T05:00"),
                 "display_name": "The Ancient Greek Hero",
@@ -157,31 +146,16 @@ class SplitModuleTest(unittest.TestCase):
                         ("course", "head12345"): {
                             "end": _date_field.from_json("2013-04-13T04:30"),
                             "tabs": [
-                                {
-                                    "type": "courseware"
-                                },
-                                {
-                                    "type": "course_info",
-                                    "name": "Course Info"
-                                },
-                                {
-                                    "type": "discussion",
-                                    "name": "Discussion"
-                                },
-                                {
-                                    "type": "wiki",
-                                    "name": "Wiki"
-                                },
-                                {
-                                    "type": "static_tab",
-                                    "name": "Syllabus",
-                                    "url_slug": "01356a17b5924b17a04b7fc2426a3798"
-                                },
-                                {
-                                    "type": "static_tab",
-                                    "name": "Advice for Students",
-                                    "url_slug": "57e9991c0d794ff58f7defae3e042e39"
-                                }
+                                CourseTab.load('courseware'),
+                                CourseTab.load('course_info'),
+                                CourseTab.load('discussion'),
+                                CourseTab.load('wiki'),
+                                CourseTab.load(
+                                    'static_tab', name="Syllabus", url_slug="01356a17b5924b17a04b7fc2426a3798"
+                                ),
+                                CourseTab.load(
+                                    'static_tab', name="Advice for Students", url_slug="57e9991c0d794ff58f7defae3e042e"
+                                ),
                             ],
                             "graceperiod": _time_delta_field.from_json("2 hours 0 minutes 0 seconds"),
                             "grading_policy": {
@@ -345,21 +319,10 @@ class SplitModuleTest(unittest.TestCase):
             "user_id": TEST_USER_ID,
             "fields": {
                 "tabs": [
-                    {
-                        "type": "courseware"
-                    },
-                    {
-                        "type": "course_info",
-                        "name": "Course Info"
-                    },
-                    {
-                        "type": "discussion",
-                        "name": "Discussion"
-                    },
-                    {
-                        "type": "wiki",
-                        "name": "Wiki"
-                    }
+                    CourseTab.load('courseware'),
+                    CourseTab.load('course_info'),
+                    CourseTab.load('discussion'),
+                    CourseTab.load('wiki'),
                 ],
                 "start": _date_field.from_json("2013-02-14T05:00"),
                 "display_name": "A wonderful course",
@@ -453,21 +416,10 @@ class SplitModuleTest(unittest.TestCase):
             "user_id": TEST_GUEST_USER_ID,
             "fields": {
                 "tabs": [
-                    {
-                        "type": "courseware"
-                    },
-                    {
-                        "type": "course_info",
-                        "name": "Course Info"
-                    },
-                    {
-                        "type": "discussion",
-                        "name": "Discussion"
-                    },
-                    {
-                        "type": "wiki",
-                        "name": "Wiki"
-                    }
+                    CourseTab.load('courseware'),
+                    CourseTab.load('course_info'),
+                    CourseTab.load('discussion'),
+                    CourseTab.load('wiki'),
                 ],
                 "start": _date_field.from_json("2013-03-14T05:00"),
                 "display_name": "Yet another contender",
@@ -582,8 +534,7 @@ class SplitModuleTest(unittest.TestCase):
 class TestHasChildrenAtDepth(SplitModuleTest):
     """Test the has_children_at_depth method of XModuleMixin. """
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_has_children_at_depth(self, _from_json):
+    def test_has_children_at_depth(self):
         course_locator = CourseLocator(
             org='testx', course='GreekHero', run="run", branch=BRANCH_NAME_DRAFT
         )
@@ -622,8 +573,7 @@ class SplitModuleCourseTests(SplitModuleTest):
     Course CRUD operation tests
     '''
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_courses(self, _from_json):
+    def test_get_courses(self):
         courses = modulestore().get_courses(branch=BRANCH_NAME_DRAFT)
         # should have gotten 3 draft courses
         assert len(courses) == 3, 'Wrong number of courses'
@@ -639,8 +589,7 @@ class SplitModuleCourseTests(SplitModuleTest):
         assert course.edited_by == TEST_ASSISTANT_USER_ID
         self.assertDictEqual(course.grade_cutoffs, {"Pass": 0.45})
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_courses_with_same_course_index(self, _from_json):
+    def test_get_courses_with_same_course_index(self):
         """
         Test that if two courses point to same course index,
         `get_courses` should return both courses.
@@ -659,8 +608,7 @@ class SplitModuleCourseTests(SplitModuleTest):
         assert len(courses) == 4
         assert new_draft_course.id.version_agnostic() in [c.id for c in courses]
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_org_courses(self, _from_json):
+    def test_get_org_courses(self):
         courses = modulestore().get_courses(branch=BRANCH_NAME_DRAFT, org='guestx')
 
         # should have gotten 1 draft courses
@@ -677,8 +625,7 @@ class SplitModuleCourseTests(SplitModuleTest):
         courses = modulestore().get_courses(branch=BRANCH_NAME_DRAFT)
         assert len(courses) == 3
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_branch_requests(self, _from_json):
+    def test_branch_requests(self):
         # query w/ branch qualifier (both draft and published)
         def _verify_published_course(courses_published):
             """ Helper function for verifying published course. """
@@ -706,8 +653,7 @@ class SplitModuleCourseTests(SplitModuleTest):
             locator_key_fields=['org', 'course', 'run']
         )
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_course(self, _from_json):
+    def test_get_course(self):
         '''
         Test the various calling forms for get_course
         '''
@@ -760,8 +706,7 @@ class SplitModuleCourseTests(SplitModuleTest):
         with pytest.raises(ItemNotFoundError):
             modulestore().get_course(CourseLocator(org='testx', course='GreekHero', run="run", branch=BRANCH_NAME_PUBLISHED))  # lint-amnesty, pylint: disable=line-too-long
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_cache(self, _from_json):
+    def test_cache(self):
         """
         Test that the mechanics of caching work.
         """
@@ -773,8 +718,7 @@ class SplitModuleCourseTests(SplitModuleTest):
         assert BlockKey('chapter', 'chapter1') in block_map
         assert BlockKey('problem', 'problem3_2') in block_map
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_persist_dag(self, _from_json):
+    def test_persist_dag(self):
         """
         try saving temporary xblocks
         """
@@ -919,8 +863,7 @@ class SplitModuleItemTests(SplitModuleTest):
     Item read tests including inheritance
     '''
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_has_item(self, _from_json):
+    def test_has_item(self):
         '''
         has_item(BlockUsageLocator)
         '''
@@ -969,8 +912,7 @@ class SplitModuleItemTests(SplitModuleTest):
         )
         assert not modulestore().has_item(locator)
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_item(self, _from_json):
+    def test_get_item(self):
         '''
         get_item(blocklocator)
         '''
@@ -1126,8 +1068,7 @@ class SplitModuleItemTests(SplitModuleTest):
         parent = modulestore().get_parent_location(locator)
         assert parent is None
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_get_children(self, _from_json):
+    def test_get_children(self):
         """
         Test the existing get_children method on xdescriptors
         """
@@ -1482,8 +1423,7 @@ class TestItemCrud(SplitModuleTest):
         other_updated = modulestore().update_item(other_block, self.user_id)
         assert moved_child.version_agnostic() in version_agnostic(other_updated.children)
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_update_definition(self, _from_json):
+    def test_update_definition(self):
         """
         test updating an item's definition: ensure it gets versioned as well as the course getting versioned
         """
@@ -1752,8 +1692,7 @@ class TestCourseCreation(SplitModuleTest):
             fields['grading_policy']['GRADE_CUTOFFS']
         )
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_update_course_index(self, _from_json):
+    def test_update_course_index(self):
         """
         Test the versions pointers. NOTE: you can change the org, course, or other things, but
         it's not clear how you'd find them again or associate them w/ existing student history since
@@ -1808,8 +1747,7 @@ class TestCourseCreation(SplitModuleTest):
                 dupe_course_key.org, dupe_course_key.course, dupe_course_key.run, user, BRANCH_NAME_DRAFT
             )
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_bulk_ops_get_courses(self, _from_json):
+    def test_bulk_ops_get_courses(self):
         """
         Test get_courses when some are created, updated, and deleted w/in a bulk operation
         """
@@ -1848,8 +1786,7 @@ class TestInheritance(SplitModuleTest):
     """
     Test the metadata inheritance mechanism.
     """
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_inheritance(self, _from_json):
+    def test_inheritance(self):
         """
         The actual test
         """
@@ -1923,8 +1860,7 @@ class TestPublish(SplitModuleTest):
     """
     Test the publishing api
     """
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_publish_safe(self, _from_json):
+    def test_publish_safe(self):
         """
         Test the standard patterns: publish to new branch, revise and publish
         """
@@ -1991,8 +1927,7 @@ class TestPublish(SplitModuleTest):
         with pytest.raises(ItemNotFoundError):
             modulestore().copy(self.user_id, source_course, destination_course, [problem1], [])
 
-    @patch('xmodule.tabs.CourseTab.from_json', side_effect=mock_tab_from_json)
-    def test_move_delete(self, _from_json):
+    def test_move_delete(self):
         """
         Test publishing moves and deletes.
         """
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/utils.py b/common/lib/xmodule/xmodule/modulestore/tests/utils.py
index f59d7b6b75..78e2760ab2 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/utils.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/utils.py
@@ -64,14 +64,6 @@ def create_modulestore_instance(
     )
 
 
-def mock_tab_from_json(tab_dict):
-    """
-    Mocks out the CourseTab.from_json to just return the tab_dict itself so that we don't have to deal
-    with plugin errors.
-    """
-    return tab_dict
-
-
 def add_temp_files_from_dict(file_dict, dir):  # lint-amnesty, pylint: disable=redefined-builtin
     """
     Takes in a dict formatted as: { file_name: content }, and adds files to directory
diff --git a/common/lib/xmodule/xmodule/tabs.py b/common/lib/xmodule/xmodule/tabs.py
index 099aa84a45..1292db60ac 100644
--- a/common/lib/xmodule/xmodule/tabs.py
+++ b/common/lib/xmodule/xmodule/tabs.py
@@ -381,7 +381,6 @@ class CourseTabList(List):
         __init__ method.  This is because the default values are dependent on other information from
         within the course.
         """
-
         course_tabs = [
             CourseTab.load('course_info'),
             CourseTab.load('courseware')
@@ -406,11 +405,20 @@ class CourseTabList(List):
             discussion_tab,
             CourseTab.load('wiki'),
             CourseTab.load('progress'),
+            CourseTab.load('dates'),
         ])
-        # While you should be able to do `tab.priority`, a lot of tests mock tabs to be a dict
-        # which causes them to throw an error on this line
-        course_tabs.sort(key=lambda tab: getattr(tab, 'priority', None) or float('inf'))
-        course.tabs.extend(course_tabs)
+
+        # Cross reference existing slugs with slugs this method would add to not add duplicates.
+        existing_tab_slugs = {tab.type for tab in course.tabs if course.tabs}
+        tabs_to_add = []
+        for tab in course_tabs:
+            if tab.type not in existing_tab_slugs:
+                tabs_to_add.append(tab)
+
+        if tabs_to_add:
+            tabs_to_add.extend(course.tabs)
+            tabs_to_add.sort(key=lambda tab: tab.priority or float('inf'))
+            course.tabs = tabs_to_add
 
     @staticmethod
     def get_discussion(course):
diff --git a/lms/djangoapps/courseware/tabs.py b/lms/djangoapps/courseware/tabs.py
index 9c6a8f283e..54190fa833 100644
--- a/lms/djangoapps/courseware/tabs.py
+++ b/lms/djangoapps/courseware/tabs.py
@@ -367,10 +367,8 @@ def get_course_tab_list(user, course):
         if tab.type == 'static_tab' and tab.course_staff_only and \
                 not bool(user and has_access(user, 'staff', course, course.id)):
             continue
-        # We had initially created a CourseTab.load() for dates that ended up
-        # persisting the dates tab tomodulestore on Course Run creation, but
-        # ignoring any static dates tab here we can fix forward without
-        # allowing the bug to continue to surface
+        # We are phasing this out in https://github.com/openedx/edx-platform/pull/30045/, but need this
+        # until the backfill course tabs command is completed
         if tab.type == 'dates':
             continue
         course_tab_list.append(tab)
diff --git a/openedx/core/djangoapps/content/course_overviews/management/commands/simulate_publish.py b/openedx/core/djangoapps/content/course_overviews/management/commands/simulate_publish.py
index 177fb8f31f..f4736c6b3e 100644
--- a/openedx/core/djangoapps/content/course_overviews/management/commands/simulate_publish.py
+++ b/openedx/core/djangoapps/content/course_overviews/management/commands/simulate_publish.py
@@ -85,7 +85,7 @@ class Command(BaseCommand):
             dest='show_receivers',
             action='store_true',
             help=('Display the list of possible receiver functions and exit.')
-        ),  # lint-amnesty, pylint: disable=trailing-comma-tuple
+        )
         parser.add_argument(
             '--dry-run',
             dest='dry_run',
@@ -95,7 +95,7 @@ class Command(BaseCommand):
                 "expensive modulestore query to find courses, but it will "
                 "not emit any signals."
             )
-        ),  # lint-amnesty, pylint: disable=trailing-comma-tuple
+        )
         parser.add_argument(
             '--receivers',
             dest='receivers',
@@ -141,7 +141,7 @@ class Command(BaseCommand):
                 "process. However, if you know what you're doing and need to "
                 "override that behavior, use this flag."
             )
-        ),  # lint-amnesty, pylint: disable=trailing-comma-tuple
+        )
         parser.add_argument(
             '--skip-ccx',
             dest='skip_ccx',
@@ -155,12 +155,12 @@ class Command(BaseCommand):
                 "if you know what you're doing, you can disable this behavior "
                 "with this flag, so that CCX receivers are omitted."
             )
-        ),  # lint-amnesty, pylint: disable=trailing-comma-tuple
+        )
         parser.add_argument(
             '--args-from-database',
             action='store_true',
             help='Use arguments from the SimulateCoursePublishConfig model instead of the command line.',
-        ),  # lint-amnesty, pylint: disable=trailing-comma-tuple
+        )
 
     def get_args_from_database(self):
         """ Returns an options dictionary from the current SimulateCoursePublishConfig model. """
diff --git a/openedx/core/djangoapps/content/course_overviews/tests/test_course_overviews.py b/openedx/core/djangoapps/content/course_overviews/tests/test_course_overviews.py
index 04ed90de15..d9b8859a60 100644
--- a/openedx/core/djangoapps/content/course_overviews/tests/test_course_overviews.py
+++ b/openedx/core/djangoapps/content/course_overviews/tests/test_course_overviews.py
@@ -62,7 +62,7 @@ class CourseOverviewTestCase(CatalogIntegrationMixin, ModuleStoreTestCase, Cache
         None: None,
     }
 
-    COURSE_OVERVIEW_TABS = {'courseware', 'info', 'textbooks', 'discussion', 'wiki', 'progress'}
+    COURSE_OVERVIEW_TABS = {'courseware', 'info', 'textbooks', 'discussion', 'wiki', 'progress', 'dates'}
 
     ENABLED_SIGNALS = ['course_deleted', 'course_published']