diff --git a/app/Http/Requests/Admin/HR/LeaveRequestRequest.php b/app/Http/Requests/Admin/HR/LeaveRequestRequest.php
index afca887..66c06d8 100644
--- a/app/Http/Requests/Admin/HR/LeaveRequestRequest.php
+++ b/app/Http/Requests/Admin/HR/LeaveRequestRequest.php
@@ -2,6 +2,7 @@
 
 namespace App\Http\Requests\Admin\HR;
 
+use App\Models\LeaveRequest;
 use Illuminate\Foundation\Http\FormRequest;
 
 class LeaveRequestRequest extends FormRequest
@@ -13,8 +14,33 @@ public function authorize(): bool
 
     public function rules(): array
     {
+        $leaveRequest = $this->route('leaveRequest');
+
         return [
-            'start_date' => ['required', 'date', 'after_or_equal:today'],
+            'start_date' => [
+                'required',
+                'date',
+                'after:today',
+                function ($attribute, $value, $fail) use ($leaveRequest) {
+                    $employee = $this->user()->employee;
+
+                    if (! $employee) {
+                        return;
+                    }
+
+                    $query = LeaveRequest::where('employee_id', $employee->id)
+                        ->where('start_date', $value)
+                        ->where('status', '!=', 'cancelled');
+
+                    if ($leaveRequest) {
+                        $query->where('id', '!=', $leaveRequest->id);
+                    }
+
+                    if ($query->exists()) {
+                        $fail('Anda sudah mengajukan cuti pada tanggal ini.');
+                    }
+                },
+            ],
             'end_date' => ['required', 'date', 'after_or_equal:start_date'],
         ];
     }
diff --git a/docs/leave-request-validation-fix.md b/docs/leave-request-validation-fix.md
new file mode 100644
index 0000000..9f0cb4b
--- /dev/null
+++ b/docs/leave-request-validation-fix.md
@@ -0,0 +1,35 @@
+# Fix: Validasi Pengajuan Cuti & Timezone
+
+## Tujuan
+Memperbaiki 3 masalah pada modul pengajuan cuti:
+1. Timezone bug — tanggal yang dipilih mundur 1 hari (user pilih 8, ke-save 7)
+2. Tidak bisa mengajukan cuti untuk hari ini
+3. Tidak bisa mengajukan cuti di tanggal yang sama lebih dari 1x
+
+## File yang Dibaca
+- `resources/js/pages/admin/hr/leave-request/index.tsx` → Frontend form pengajuan cuti
+- `app/Http/Requests/Admin/HR/LeaveRequestRequest.php` → Validasi backend
+- `app/Services/Admin/HR/LeaveRequestService.php` → Service logic
+- `app/Models/LeaveRequest.php` → Model dengan cast `date:Y-m-d`
+
+## Pola yang Ditemukan
+- Frontend menggunakan `toISOString().split('T')[0]` untuk format tanggal → **PROBLEM**: `toISOString()` konversi ke UTC, sehingga waktu WIB (UTC+7) mundur 1 hari
+- Validasi backend hanya `after_or_equal:today` → bisa submit untuk hari ini
+- Tidak ada pengecekan duplikat tanggal cuti per employee
+
+## Perubahan
+
+### 1. Frontend — Fix Timezone (`index.tsx`)
+- Tambah helper function `toLocalDateString()` yang menggunakan `getFullYear()`, `getMonth()`, `getDate()` (local time) alih-alih `toISOString()` (UTC)
+- Ganti semua `toISOString().split('T')[0]` → `toLocalDateString(...)`
+
+### 2. Backend — Validasi Stricter (`LeaveRequestRequest.php`)
+- `start_date`: `after_or_equal:today` → `after:today` (tidak bisa hari ini)
+- Tambah custom closure rule: cek apakah employee sudah punya leave request dengan `start_date` yang sama (exclude status `cancelled` dan record sendiri saat update)
+- Error message: "Anda sudah mengajukan cuti pada tanggal ini."
+
+## Cara Kerja
+1. User pilih tanggal 8 Agustus → DatePicker simpan sebagai `Date` object (local time)
+2. `toLocalDateString()` format sebagai `"2026-08-08"` tanpa konversi UTC
+3. Backend validasi: pastikan tanggal > hari ini + belum ada cuti di tanggal yang sama
+4. Service simpan ke DB dengan cast `date:Y-m-d` → tetap `"2026-08-08"`
diff --git a/resources/js/pages/admin/hr/leave-request/index.tsx b/resources/js/pages/admin/hr/leave-request/index.tsx
index 7336f23..2b847c7 100644
--- a/resources/js/pages/admin/hr/leave-request/index.tsx
+++ b/resources/js/pages/admin/hr/leave-request/index.tsx
@@ -52,6 +52,13 @@ type Props = {
     };
 };
 
+function toLocalDateString(date: Date): string {
+    const year = date.getFullYear();
+    const month = String(date.getMonth() + 1).padStart(2, '0');
+    const day = String(date.getDate()).padStart(2, '0');
+    return `${year}-${month}-${day}`;
+}
+
 export default function LeaveRequestIndex({ leaveRequests, filters, filterOptions }: Props) {
     const { can } = useCan();
     const [createOpen, setCreateOpen] = useState(false);
@@ -225,9 +232,7 @@ export default function LeaveRequestIndex({ leaveRequests, filters, filterOption
                                     name="start_date"
                                     value={
                                         startDate
-                                            ? startDate
-                                                  .toISOString()
-                                                  .split('T')[0]
+                                            ? toLocalDateString(startDate)
                                             : ''
                                     }
                                 />
@@ -248,9 +253,7 @@ export default function LeaveRequestIndex({ leaveRequests, filters, filterOption
                                     name="end_date"
                                     value={
                                         endDate
-                                            ? endDate
-                                                  .toISOString()
-                                                  .split('T')[0]
+                                            ? toLocalDateString(endDate)
                                             : ''
                                     }
                                 />
@@ -312,9 +315,7 @@ export default function LeaveRequestIndex({ leaveRequests, filters, filterOption
                                         name="start_date"
                                         value={
                                             editingStartDate
-                                                ? editingStartDate
-                                                      .toISOString()
-                                                      .split('T')[0]
+                                                ? toLocalDateString(editingStartDate)
                                                 : ''
                                         }
                                     />
@@ -337,9 +338,7 @@ export default function LeaveRequestIndex({ leaveRequests, filters, filterOption
                                         name="end_date"
                                         value={
                                             editingEndDate
-                                                ? editingEndDate
-                                                      .toISOString()
-                                                      .split('T')[0]
+                                                ? toLocalDateString(editingEndDate)
                                                 : ''
                                         }
                                     />