diff --git a/apps/backend/src/routes/register/route.ts b/apps/backend/src/routes/register/route.ts
index 9ac5706..432637c 100644
--- a/apps/backend/src/routes/register/route.ts
+++ b/apps/backend/src/routes/register/route.ts
@@ -7,7 +7,7 @@ import { hashPassword } from "../../utils/passwordUtils";
 import requestValidator from "../../utils/requestValidator";
 import authInfo from "../../middlewares/authInfo";
 import checkPermission from "../../middlewares/checkPermission";
-import { and, eq, isNull, ilike, or, sql } from "drizzle-orm";
+import { and, eq, or } from "drizzle-orm";
 import { z } from "zod";
 import HonoEnv from "../../types/HonoEnv";
 
@@ -25,7 +25,6 @@ const registerFormSchema = z.object({
 
 const respondentsRoute = new Hono<HonoEnv>()
     .use(authInfo)
-    //create user and respondent
     .post(
         "/",
         checkPermission("register.create"),
@@ -33,6 +32,35 @@ const respondentsRoute = new Hono<HonoEnv>()
         async (c) => {
             const formData = c.req.valid("json");
 
+            // Build conditions based on available formData
+            const conditions = [];
+            if (formData.email) {
+                conditions.push(eq(users.email, formData.email));
+            }
+            conditions.push(eq(users.username, formData.username));
+
+            const existingUser = await db
+                .select()
+                .from(users)
+                .where(or(...conditions));
+
+            const existingRespondent = await db
+                .select()
+                .from(respondents)
+                .where(eq(respondents.phoneNumber, formData.phoneNumber));
+
+            if (existingUser.length > 0) {
+                throw new HTTPException(400, {
+                    message: "Email atau username sudah terdaftar",
+                });
+            }
+
+            if (existingRespondent.length > 0) {
+                throw new HTTPException(400, {
+                    message: "Nomor HP sudah terdaftar",
+                });
+            }
+
             // Hash the password
             const hashedPassword = await hashPassword(formData.password);