diff --git a/be/app/api/v1/api.py b/be/app/api/v1/api.py
index 6988405..ac49730 100644
--- a/be/app/api/v1/api.py
+++ b/be/app/api/v1/api.py
@@ -21,7 +21,7 @@ api_router_v1.include_router(invites.router, prefix="/invites", tags=["Invites"]
 api_router_v1.include_router(lists.router, prefix="/lists", tags=["Lists"]) 
 api_router_v1.include_router(items.router, tags=["Items"])
 api_router_v1.include_router(ocr.router, prefix="/ocr", tags=["OCR"])
-api_router_v1.include_router(costs.router, tags=["Costs"])
+api_router_v1.include_router(costs.router, prefix="/costs", tags=["Costs"])
 api_router_v1.include_router(financials.router)
 # Add other v1 endpoint routers here later
 # e.g., api_router_v1.include_router(users.router, prefix="/users", tags=["Users"])
\ No newline at end of file
diff --git a/be/app/api/v1/endpoints/costs.py b/be/app/api/v1/endpoints/costs.py
index ff6e158..1288dc8 100644
--- a/be/app/api/v1/endpoints/costs.py
+++ b/be/app/api/v1/endpoints/costs.py
@@ -69,7 +69,7 @@ async def get_list_cost_summary(
         select(ListModel)
         .options(
             selectinload(ListModel.items).options(selectinload(ItemModel.added_by_user)),
-            selectinload(ListModel.group).options(selectinload(GroupModel.user_associations).options(selectinload(UserGroupModel.user))),
+            selectinload(ListModel.group).options(selectinload(GroupModel.member_associations).options(selectinload(UserGroupModel.user))),
             selectinload(ListModel.creator)
         )
         .where(ListModel.id == list_id)