diff --git a/app/Filament/Resources/MemberDues/Schemas/MemberDueForm.php b/app/Filament/Resources/MemberDues/Schemas/MemberDueForm.php
index 7f137ca..4005aa0 100644
--- a/app/Filament/Resources/MemberDues/Schemas/MemberDueForm.php
+++ b/app/Filament/Resources/MemberDues/Schemas/MemberDueForm.php
@@ -19,6 +19,8 @@ class MemberDueForm
                 ->searchable()->required(),
             TextInput::make('period')->label('Periode (YYYY-MM)')
                 ->placeholder(now()->format('Y-m'))
+                ->rules(['regex:/^\d{4}-(0[1-9]|1[0-2])$/'])
+                ->validationMessages(['regex' => 'Format periode harus YYYY-MM (contoh: 2026-05).'])
                 ->required(),
             TextInput::make('amount')->label('Jumlah (Rp)')->numeric()->required(),
             Select::make('status')->options(['lunas' => 'Lunas', 'belum' => 'Belum Lunas'])