diff --git a/backend/app/api/todos.py b/backend/app/api/todos.py
index 52fda31..f03392b 100644
--- a/backend/app/api/todos.py
+++ b/backend/app/api/todos.py
@@ -18,8 +18,8 @@ async def list_todos(
     status: str | None = "pending",
     priority: str | None = None,
     tag: str | None = None,
-    due_after: str | None = None,
-    due_before: str | None = None,
+    due_after: datetime | None = None,
+    due_before: datetime | None = None,
     limit: int = 200,
     session: AsyncSession = Depends(get_session),
 ):
@@ -33,13 +33,14 @@ async def list_todos(
     if tag:
         conditions.append(TodoItem.tags.contains([tag]))
     if due_after:
-        conditions.append(TodoItem.due_date >= datetime.fromisoformat(due_after))
+        conditions.append(TodoItem.due_date >= due_after)
     if due_before:
-        conditions.append(TodoItem.due_date <= datetime.fromisoformat(due_before))
+        conditions.append(TodoItem.due_date <= due_before)
 
     stmt = select(TodoItem)
     if conditions:
         stmt = stmt.where(and_(*conditions))
+    stmt = stmt.order_by(TodoItem.due_date.asc().nulls_last(), TodoItem.created_at.desc())
     stmt = stmt.limit(limit)
     result = await session.execute(stmt)
     return result.scalars().all()