diff --git a/userfront/lib/core/services/auth_proxy_service.dart b/userfront/lib/core/services/auth_proxy_service.dart
index 534813b2..57d1e723 100644
--- a/userfront/lib/core/services/auth_proxy_service.dart
+++ b/userfront/lib/core/services/auth_proxy_service.dart
@@ -893,7 +893,10 @@ class AuthProxyService {
     return false;
   }
 
-  static Future<Map<String, dynamic>> checkLoginIDAvailability(String loginId, {String? companyCode}) async {
+  static Future<Map<String, dynamic>> checkLoginIDAvailability(
+    String loginId, {
+    String? companyCode,
+  }) async {
     final url = Uri.parse('$_baseUrl/api/v1/auth/signup/check-login-id');
     final bodyData = {'loginId': loginId};
     if (companyCode != null && companyCode.isNotEmpty) {
@@ -907,10 +910,16 @@ class AuthProxyService {
 
     if (response.statusCode == 200) {
       final data = jsonDecode(response.body);
-      return {'available': data['available'] ?? false, 'message': data['message']};
+      return {
+        'available': data['available'] ?? false,
+        'message': data['message'],
+      };
     } else {
       final data = jsonDecode(response.body);
-      return {'available': false, 'message': data['message'] ?? 'Failed to check ID'};
+      return {
+        'available': false,
+        'message': data['message'] ?? 'Failed to check ID',
+      };
     }
   }
 
diff --git a/userfront/lib/features/auth/presentation/login_screen.dart b/userfront/lib/features/auth/presentation/login_screen.dart
index 86f08faf..3d3fc2ad 100644
--- a/userfront/lib/features/auth/presentation/login_screen.dart
+++ b/userfront/lib/features/auth/presentation/login_screen.dart
@@ -1470,9 +1470,11 @@ class _LoginScreenState extends ConsumerState<LoginScreen>
                                     ),
                                     controller: _passwordLoginIdController,
                                     decoration: InputDecoration(
-                                      labelText: _loginIdLabel ?? tr(
-                                        'ui.userfront.login.field.login_id',
-                                      ),
+                                      labelText:
+                                          _loginIdLabel ??
+                                          tr(
+                                            'ui.userfront.login.field.login_id',
+                                          ),
                                       border: const OutlineInputBorder(),
                                       prefixIcon: const Icon(
                                         Icons.person_outline,
diff --git a/userfront/lib/features/auth/presentation/signup_screen.dart b/userfront/lib/features/auth/presentation/signup_screen.dart
index 330a8f12..e6fffa74 100644
--- a/userfront/lib/features/auth/presentation/signup_screen.dart
+++ b/userfront/lib/features/auth/presentation/signup_screen.dart
@@ -1446,42 +1446,68 @@ class _SignupScreenState extends State<SignupScreen> {
                               border: const OutlineInputBorder(),
                               errorText: _loginIdError,
                               suffixIcon: TextButton(
-                                onPressed: _isLoading ? null : () async {
-                                  final loginId = _loginIdController.text.trim();
-                                  if (loginId.isEmpty) {
-                                    setState(() => _loginIdError = 'ID를 입력해주세요.');
-                                    return;
-                                  }
-                                  setState(() {
-                                    _isLoading = true;
-                                    _loginIdError = null;
-                                    _loginIdSuccess = null;
-                                  });
-                                  try {
-                                    final result = await AuthProxyService.checkLoginIDAvailability(loginId, companyCode: _affiliationType == 'AFFILIATE' ? _companyCode : null);
-                                    setState(() {
-                                      if (result['available'] == true) {
-                                        _loginIdSuccess = '사용 가능한 ID입니다.';
-                                      } else {
-                                        _loginIdError = result['message'] ?? '사용할 수 없는 ID입니다.';
-                                      }
-                                    });
-                                  } catch (e) {
-                                    setState(() => _loginIdError = e.toString().replaceAll('Exception: ', ''));
-                                  } finally {
-                                    if (mounted) setState(() => _isLoading = false);
-                                  }
-                                },
+                                onPressed: _isLoading
+                                    ? null
+                                    : () async {
+                                        final loginId = _loginIdController.text
+                                            .trim();
+                                        if (loginId.isEmpty) {
+                                          setState(
+                                            () => _loginIdError = 'ID를 입력해주세요.',
+                                          );
+                                          return;
+                                        }
+                                        setState(() {
+                                          _isLoading = true;
+                                          _loginIdError = null;
+                                          _loginIdSuccess = null;
+                                        });
+                                        try {
+                                          final result =
+                                              await AuthProxyService.checkLoginIDAvailability(
+                                                loginId,
+                                                companyCode:
+                                                    _affiliationType ==
+                                                        'AFFILIATE'
+                                                    ? _companyCode
+                                                    : null,
+                                              );
+                                          setState(() {
+                                            if (result['available'] == true) {
+                                              _loginIdSuccess = '사용 가능한 ID입니다.';
+                                            } else {
+                                              _loginIdError =
+                                                  result['message'] ??
+                                                  '사용할 수 없는 ID입니다.';
+                                            }
+                                          });
+                                        } catch (e) {
+                                          setState(
+                                            () => _loginIdError = e
+                                                .toString()
+                                                .replaceAll('Exception: ', ''),
+                                          );
+                                        } finally {
+                                          if (mounted)
+                                            setState(() => _isLoading = false);
+                                        }
+                                      },
                                 child: const Text('중복 확인'),
                               ),
                             ),
                           ),
                           if (_loginIdSuccess != null)
                             Padding(
-                              padding: const EdgeInsets.only(top: 8.0, left: 12.0),
+                              padding: const EdgeInsets.only(
+                                top: 8.0,
+                                left: 12.0,
+                              ),
                               child: Text(
                                 _loginIdSuccess!,
-                                style: const TextStyle(color: Colors.green, fontSize: 12),
+                                style: const TextStyle(
+                                  color: Colors.green,
+                                  fontSize: 12,
+                                ),
                               ),
                             ),
                         ],