diff --git a/auth-migration/src/main/java/com/example/auth/security/CustomAccessDeniedHandler.java b/auth-migration/src/main/java/com/example/auth/security/CustomAccessDeniedHandler.java
new file mode 100644
index 0000000..634cebd
--- /dev/null
+++ b/auth-migration/src/main/java/com/example/auth/security/CustomAccessDeniedHandler.java
@@ -0,0 +1,46 @@
+package com.example.auth.security;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.springframework.http.MediaType;
+import org.springframework.security.access.AccessDeniedException;
+import org.springframework.security.web.access.AccessDeniedHandler;
+import org.springframework.stereotype.Component;
+
+import java.io.IOException;
+import java.time.Instant;
+import java.util.Map;
+
+/**
+ * Custom Access Denied Handler - preserves error response format.
+ * Maps to AUTH_030, AUTH_031, AUTH_040, AUTH_041 error codes.
+ */
+@Component
+public class CustomAccessDeniedHandler implements AccessDeniedHandler {
+
+    private final ObjectMapper objectMapper;
+
+    public CustomAccessDeniedHandler(ObjectMapper objectMapper) {
+        this.objectMapper = objectMapper;
+    }
+
+    @Override
+    public void handle(
+            HttpServletRequest request,
+            HttpServletResponse response,
+            AccessDeniedException accessDeniedException) throws IOException {
+
+        response.setStatus(HttpServletResponse.SC_FORBIDDEN);
+        response.setContentType(MediaType.APPLICATION_JSON_VALUE);
+
+        Map<String, Object> errorResponse = Map.of(
+                "code", "AUTH_030",
+                "message", "Insufficient permissions",
+                "timestamp", Instant.now().toString(),
+                "path", request.getRequestURI()
+        );
+
+        objectMapper.writeValue(response.getOutputStream(), errorResponse);
+    }
+}