diff --git a/frontend/src/api.ts b/frontend/src/api.ts
index 18cea36..a978ce7 100644
--- a/frontend/src/api.ts
+++ b/frontend/src/api.ts
@@ -58,11 +58,11 @@ export async function deleteItemTag(itemId: string, tagId: string): Promise<Item
   return res.json();
 }
 
-export async function addItemTag(itemId: string, tagName: string): Promise<Item> {
+export async function addItemTag(itemId: string, tagId: string): Promise<Item> {
   const res = await fetch(`${API_BASE}/items/${itemId}/tags`, {
     method: "POST",
     headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ name: tagName }),
+    body: JSON.stringify({ tag_id: tagId }),
   });
   if (!res.ok) throw new Error("Failed to add tag to item");
   return res.json();
diff --git a/frontend/src/pages/ItemsPage.tsx b/frontend/src/pages/ItemsPage.tsx
index e66a3a1..9692574 100644
--- a/frontend/src/pages/ItemsPage.tsx
+++ b/frontend/src/pages/ItemsPage.tsx
@@ -55,8 +55,8 @@ export default function ItemsPage() {
     setItems((prev) => prev.map((it) => (it.id === itemId ? updated : it)));
   }
 
-  async function handleAddTag(itemId: string, tagName: string) {
-    const updated = await addItemTag(itemId, tagName);
+  async function handleAddTag(itemId: string, tagId: string) {
+    const updated = await addItemTag(itemId, tagId);
     setItems((prev) => prev.map((it) => (it.id === itemId ? updated : it)));
   }