diff --git a/backend/alembic/versions/060_expand_notification_types_project.py b/backend/alembic/versions/060_expand_notification_types_project.py
new file mode 100644
index 0000000..723295d
--- /dev/null
+++ b/backend/alembic/versions/060_expand_notification_types_project.py
@@ -0,0 +1,35 @@
+"""Expand notification type CHECK for project invite types
+
+Revision ID: 060
+Revises: 059
+"""
+from alembic import op
+
+revision = "060"
+down_revision = "059"
+branch_labels = None
+depends_on = None
+
+_OLD_TYPES = (
+    "connection_request", "connection_accepted", "connection_rejected",
+    "calendar_invite", "calendar_invite_accepted", "calendar_invite_rejected",
+    "event_invite", "event_invite_response",
+    "info", "warning", "reminder", "system",
+)
+_NEW_TYPES = _OLD_TYPES + (
+    "project_invite", "project_invite_accepted", "project_invite_rejected",
+)
+
+
+def _check_sql(types: tuple) -> str:
+    return f"type IN ({', '.join(repr(t) for t in types)})"
+
+
+def upgrade() -> None:
+    op.drop_constraint("ck_notifications_type", "notifications", type_="check")
+    op.create_check_constraint("ck_notifications_type", "notifications", _check_sql(_NEW_TYPES))
+
+
+def downgrade() -> None:
+    op.drop_constraint("ck_notifications_type", "notifications", type_="check")
+    op.create_check_constraint("ck_notifications_type", "notifications", _check_sql(_OLD_TYPES))
diff --git a/backend/app/models/notification.py b/backend/app/models/notification.py
index e0d6f47..676be3e 100644
--- a/backend/app/models/notification.py
+++ b/backend/app/models/notification.py
@@ -9,6 +9,7 @@ _NOTIFICATION_TYPES = (
     "connection_request", "connection_accepted", "connection_rejected",
     "calendar_invite", "calendar_invite_accepted", "calendar_invite_rejected",
     "event_invite", "event_invite_response",
+    "project_invite", "project_invite_accepted", "project_invite_rejected",
     "info", "warning", "reminder", "system",
 )