diff --git a/src/documents/tests/test_tag_hierarchy.py b/src/documents/tests/test_tag_hierarchy.py
new file mode 100644
index 000000000..525ebae26
--- /dev/null
+++ b/src/documents/tests/test_tag_hierarchy.py
@@ -0,0 +1,92 @@
+from django.contrib.auth.models import User
+from rest_framework.test import APITestCase
+
+from documents import bulk_edit
+from documents.models import Document
+from documents.models import Tag
+from documents.models import Workflow
+from documents.models import WorkflowAction
+from documents.models import WorkflowTrigger
+from documents.signals.handlers import run_workflows
+
+
+class TestTagHierarchy(APITestCase):
+    def setUp(self):
+        self.user = User.objects.create_superuser(username="admin")
+        self.client.force_authenticate(user=self.user)
+
+        self.parent = Tag.objects.create(name="Parent")
+        self.child = Tag.objects.create(name="Child", parent=self.parent)
+
+        self.document = Document.objects.create(
+            title="doc",
+            content="",
+            checksum="1",
+            mime_type="application/pdf",
+        )
+
+    def test_api_add_child_adds_parent(self):
+        self.client.patch(
+            f"/api/documents/{self.document.pk}/",
+            {"tags": [self.child.pk]},
+            format="json",
+        )
+        self.document.refresh_from_db()
+        tags = set(self.document.tags.values_list("pk", flat=True))
+        assert tags == {self.parent.pk, self.child.pk}
+
+    def test_api_remove_parent_removes_child(self):
+        self.document.add_nested_tags([self.child])
+        self.client.patch(
+            f"/api/documents/{self.document.pk}/",
+            {"tags": []},
+            format="json",
+        )
+        self.document.refresh_from_db()
+        assert self.document.tags.count() == 0
+
+    def test_bulk_edit_respects_hierarchy(self):
+        bulk_edit.add_tag([self.document.pk], self.child.pk)
+        self.document.refresh_from_db()
+        tags = set(self.document.tags.values_list("pk", flat=True))
+        assert tags == {self.parent.pk, self.child.pk}
+
+        bulk_edit.remove_tag([self.document.pk], self.parent.pk)
+        self.document.refresh_from_db()
+        assert self.document.tags.count() == 0
+
+        bulk_edit.modify_tags([self.document.pk], [self.child.pk], [])
+        self.document.refresh_from_db()
+        tags = set(self.document.tags.values_list("pk", flat=True))
+        assert tags == {self.parent.pk, self.child.pk}
+
+        bulk_edit.modify_tags([self.document.pk], [], [self.parent.pk])
+        self.document.refresh_from_db()
+        assert self.document.tags.count() == 0
+
+    def test_workflow_actions(self):
+        workflow = Workflow.objects.create(name="wf", order=0)
+        trigger = WorkflowTrigger.objects.create(
+            type=WorkflowTrigger.WorkflowTriggerType.DOCUMENT_ADDED,
+        )
+        assign_action = WorkflowAction.objects.create()
+        assign_action.assign_tags.add(self.child)
+        workflow.triggers.add(trigger)
+        workflow.actions.add(assign_action)
+
+        run_workflows(trigger.type, self.document)
+        self.document.refresh_from_db()
+        tags = set(self.document.tags.values_list("pk", flat=True))
+        assert tags == {self.parent.pk, self.child.pk}
+
+        # removal
+        removal_action = WorkflowAction.objects.create(
+            type=WorkflowAction.WorkflowActionType.REMOVAL,
+        )
+        removal_action.remove_tags.add(self.parent)
+        workflow.actions.clear()
+        workflow.actions.add(removal_action)
+
+        run_workflows(trigger.type, self.document)
+        self.document.refresh_from_db()
+        assert self.document.tags.count() == 0