diff --git a/src/hasura/honor.ts b/src/hasura/honor.ts
index 2fab786b8..d91bd2e20 100644
--- a/src/hasura/honor.ts
+++ b/src/hasura/honor.ts
@@ -37,6 +37,67 @@ export const query_honor_application = async (id: string) => {
   return query.honor_application_by_pk ?? null;
 };
 
+export const query_honor_application_by_student_honor_year = async (
+  student_uuid: string,
+  honor: string,
+  year: number,
+) => {
+  const query: any = await client.request(
+    gql`
+      query QueryHonorApplicationByStudentHonorYear(
+        $student_uuid: uuid!
+        $honor: String!
+        $year: Int!
+      ) {
+        honor_application(
+          limit: 1
+          where: {
+            student_uuid: { _eq: $student_uuid }
+            honor: { _eq: $honor }
+            year: { _eq: $year }
+          }
+        ) {
+          id
+        }
+      }
+    `,
+    { student_uuid, honor, year },
+  );
+  return query.honor_application?.[0] ?? null;
+};
+
+export const query_other_honor_application_by_student_honor_year = async (
+  student_uuid: string,
+  honor: string,
+  year: number,
+  excluded_id: string,
+) => {
+  const query: any = await client.request(
+    gql`
+      query QueryOtherHonorApplicationByStudentHonorYear(
+        $student_uuid: uuid!
+        $honor: String!
+        $year: Int!
+        $excluded_id: uuid!
+      ) {
+        honor_application(
+          limit: 1
+          where: {
+            student_uuid: { _eq: $student_uuid }
+            honor: { _eq: $honor }
+            year: { _eq: $year }
+            id: { _neq: $excluded_id }
+          }
+        ) {
+          id
+        }
+      }
+    `,
+    { student_uuid, honor, year, excluded_id },
+  );
+  return query.honor_application?.[0] ?? null;
+};
+
 export const insert_honor_application = async (
   student_uuid: string,
   honor: string,
@@ -85,6 +146,7 @@ export const update_honor_application = async (
     attachment_url: attachment_url,
     application_form_url: application_form_url,
     transcript_url: transcript_url,
+    enforce_unique: true,
   };
 
   const query: any = await client.request(
diff --git a/src/routes/application.ts b/src/routes/application.ts
index 05c34937b..8a122b802 100644
--- a/src/routes/application.ts
+++ b/src/routes/application.ts
@@ -42,6 +42,10 @@ const honorNeedsApplicationForm = (honor: string) =>
   honor === GLOBAL_COMPETENCE_HONOR;
 const honorNeedsMaterialLink = (honor: string) =>
   !honorsWithoutMaterialLink.has(honor);
+const HONOR_APPLICATION_UNIQUE_CONSTRAINT =
+  "honor_application_student_uuid_year_honor_new_key";
+const isHonorApplicationDuplicateError = (err: unknown) =>
+  String(err).includes(HONOR_APPLICATION_UNIQUE_CONSTRAINT);
 const optionalString = (value: unknown): string | null => {
   if (typeof value !== "string") return null;
   const trimmed = value.trim();
@@ -264,15 +268,37 @@ router.post("/honor/insert_one", async (req, res) => {
     }
 
     const year: number = new Date().getFullYear();
-    const insert_id = await HnrHasFunc.insert_honor_application(
-      student_uuid,
-      honor,
-      statement,
-      attachment_url,
-      application_form_url,
-      transcript_url,
-      year,
-    );
+    const existingApplication =
+      await HnrHasFunc.query_honor_application_by_student_honor_year(
+        student_uuid,
+        honor,
+        year,
+      );
+    if (existingApplication) {
+      return res
+        .status(409)
+        .send("Error: You have already applied for this honor this year");
+    }
+
+    let insert_id: string | null;
+    try {
+      insert_id = await HnrHasFunc.insert_honor_application(
+        student_uuid,
+        honor,
+        statement,
+        attachment_url,
+        application_form_url,
+        transcript_url,
+        year,
+      );
+    } catch (err) {
+      if (isHonorApplicationDuplicateError(err)) {
+        return res
+          .status(409)
+          .send("Error: You have already applied for this honor this year");
+      }
+      throw err;
+    }
     if (!insert_id) {
       return res.status(452).send("Error: Insert honor application failed");
     }
@@ -330,14 +356,37 @@ router.post("/honor/update_one", async (req, res) => {
       return res.status(453).send("Error: Invalid year");
     }
 
-    const response = await HnrHasFunc.update_honor_application(
-      id,
-      honor,
-      statement,
-      attachment_url,
-      application_form_url,
-      transcript_url,
-    );
+    const existingApplication =
+      await HnrHasFunc.query_other_honor_application_by_student_honor_year(
+        application.student_uuid,
+        honor,
+        year,
+        id,
+      );
+    if (existingApplication) {
+      return res
+        .status(409)
+        .send("Error: You have already applied for this honor this year");
+    }
+
+    let response: string | null;
+    try {
+      response = await HnrHasFunc.update_honor_application(
+        id,
+        honor,
+        statement,
+        attachment_url,
+        application_form_url,
+        transcript_url,
+      );
+    } catch (err) {
+      if (isHonorApplicationDuplicateError(err)) {
+        return res
+          .status(409)
+          .send("Error: You have already applied for this honor this year");
+      }
+      throw err;
+    }
     if (!response) {
       return res.status(454).send("Error: Update honor application failed");
     }