diff --git a/src/backend/core/migrations/0027_item_quota_excluded.py b/src/backend/core/migrations/0027_item_quota_excluded.py
new file mode 100644
index 00000000..88de409f
--- /dev/null
+++ b/src/backend/core/migrations/0027_item_quota_excluded.py
@@ -0,0 +1,16 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0026_item_item_creator_size_not_hdel_idx'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='item',
+            name='quota_excluded',
+            field=models.BooleanField(default=False, help_text="Exclude this item from its creator's storage quota computation."),
+        ),
+    ]
diff --git a/src/backend/core/migrations/0028_item_creator_size_quota_idx.py b/src/backend/core/migrations/0028_item_creator_size_quota_idx.py
new file mode 100644
index 00000000..143c9406
--- /dev/null
+++ b/src/backend/core/migrations/0028_item_creator_size_quota_idx.py
@@ -0,0 +1,26 @@
+from django.contrib.postgres.operations import AddIndexConcurrently, RemoveIndexConcurrently
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    # CREATE/DROP INDEX CONCURRENTLY cannot run inside a transaction. It avoids
+    # locking writes on the item table while the index is being built. The new
+    # index is added before the old one is removed so the storage used
+    # aggregation never loses index support during the deployment.
+    atomic = False
+
+    dependencies = [
+        ('core', '0027_item_quota_excluded'),
+    ]
+
+    operations = [
+        AddIndexConcurrently(
+            model_name='item',
+            index=models.Index(condition=models.Q(('hard_deleted_at__isnull', True), ('quota_excluded', False)), fields=['creator'], include=('size',), name='item_creator_size_quota_idx'),
+        ),
+        RemoveIndexConcurrently(
+            model_name='item',
+            name='item_creator_size_not_hdel_idx',
+        ),
+    ]
diff --git a/src/backend/core/models.py b/src/backend/core/models.py
index 993f8502..aacdf51d 100644
--- a/src/backend/core/models.py
+++ b/src/backend/core/models.py
@@ -49,7 +49,7 @@ from wopi.conversion.policy import target_extension_for
 logger = getLogger(__name__)
 
 # Item fields whose update can change the storage used by a user.
-STORAGE_USED_FIELDS = {"size", "creator", "creator_id", "hard_deleted_at"}
+STORAGE_USED_FIELDS = {"size", "creator", "creator_id", "hard_deleted_at", "quota_excluded"}
 
 
 def get_trashbin_cutoff():
@@ -1021,6 +1021,10 @@ class Item(TreeModel, BaseModel):
     mimetype = models.CharField(max_length=255, null=True, blank=True)
     main_workspace = models.BooleanField(default=False)
     size = models.BigIntegerField(null=True, blank=True)
+    quota_excluded = models.BooleanField(
+        default=False,
+        help_text=_("Exclude this item from its creator's storage quota computation."),
+    )
     description = models.TextField(null=True, blank=True)
     malware_detection_info = models.JSONField(
         null=True,
@@ -1054,8 +1058,8 @@ class Item(TreeModel, BaseModel):
             models.Index(
                 fields=["creator"],
                 include=["size"],
-                condition=models.Q(hard_deleted_at__isnull=True),
-                name="item_creator_size_not_hdel_idx",
+                condition=models.Q(hard_deleted_at__isnull=True, quota_excluded=False),
+                name="item_creator_size_quota_idx",
             ),
         ]
 
diff --git a/src/backend/core/storage/creator_storage_compute_backend.py b/src/backend/core/storage/creator_storage_compute_backend.py
index c2fb7082..d2fcfe04 100644
--- a/src/backend/core/storage/creator_storage_compute_backend.py
+++ b/src/backend/core/storage/creator_storage_compute_backend.py
@@ -15,6 +15,6 @@ class CreatorStorageComputeBackend(StorageComputeBackend):
         """
         Compute the total storage used by a set of users.
         """
-        return Item.objects.filter(creator__in=users, hard_deleted_at__isnull=True).aggregate(
-            total_size=Sum("size", default=0)
-        )["total_size"]
+        return Item.objects.filter(
+            creator__in=users, hard_deleted_at__isnull=True, quota_excluded=False
+        ).aggregate(total_size=Sum("size", default=0))["total_size"]
diff --git a/src/backend/core/tests/storage/test_creator_storage_compute_backend.py b/src/backend/core/tests/storage/test_creator_storage_compute_backend.py
index 21d9b6f0..9bacc3dd 100644
--- a/src/backend/core/tests/storage/test_creator_storage_compute_backend.py
+++ b/src/backend/core/tests/storage/test_creator_storage_compute_backend.py
@@ -39,3 +39,21 @@ def test_compute_storage_used_keeps_soft_deleted_items():
     soft_deleted.soft_delete()
 
     assert CreatorStorageComputeBackend().compute_storage_used([user]) == 350
+
+
+def test_compute_storage_used_excludes_quota_excluded_items():
+    """Items flagged as quota excluded should not count toward the storage used."""
+    user = factories.UserFactory()
+    factories.ItemFactory(creator=user, size=100)
+    factories.ItemFactory(creator=user, size=250, quota_excluded=True)
+
+    assert CreatorStorageComputeBackend().compute_storage_used([user]) == 100
+
+
+def test_compute_storage_used_only_quota_excluded_items():
+    """A user owning only quota excluded items should have a storage used of zero."""
+    user = factories.UserFactory()
+    factories.ItemFactory(creator=user, size=100, quota_excluded=True)
+    factories.ItemFactory(creator=user, size=250, quota_excluded=True)
+
+    assert CreatorStorageComputeBackend().compute_storage_used([user]) == 0
diff --git a/src/backend/core/tests/test_api_entitlements_local.py b/src/backend/core/tests/test_api_entitlements_local.py
index 379d0f8b..ba66f24e 100644
--- a/src/backend/core/tests/test_api_entitlements_local.py
+++ b/src/backend/core/tests/test_api_entitlements_local.py
@@ -419,6 +419,31 @@ def test_api_entitlements_local_cache_invalidated_on_item_save(
     assert response.json()["quota"]["usage"] == 700
 
 
+@override_settings(
+    ENTITLEMENTS_BACKEND=LOCAL_BACKEND,
+    ENTITLEMENTS_BACKEND_PARAMETERS={"default_storage_limit": 1000},
+)
+def test_api_entitlements_local_cache_invalidated_on_quota_excluded(
+    django_capture_on_commit_callbacks,
+):
+    """Flagging an item as quota excluded should invalidate the creator's cached usage."""
+    client = APIClient()
+    user = factories.UserFactory()
+    item = factories.ItemFactory(type=models.ItemTypeChoices.FILE, creator=user, size=400)
+    client.force_authenticate(user)
+
+    response = client.get("/api/v1.0/entitlements/")
+    assert response.json()["quota"]["usage"] == 400
+
+    item.quota_excluded = True
+    with django_capture_on_commit_callbacks(execute=True):
+        item.save(update_fields=["quota_excluded"])
+
+    assert cache.get(get_storage_used_cache_key(user.id)) is None
+    response = client.get("/api/v1.0/entitlements/")
+    assert response.json()["quota"]["usage"] == 0
+
+
 def test_api_entitlements_local_cache_invalidated_on_hard_delete(
     django_capture_on_commit_callbacks,
 ):