diff --git a/app/Filament/Admin/Resources/InternApplications/InternApplicationResource.php b/app/Filament/Admin/Resources/InternApplications/InternApplicationResource.php
index 1fce3b0..f523411 100644
--- a/app/Filament/Admin/Resources/InternApplications/InternApplicationResource.php
+++ b/app/Filament/Admin/Resources/InternApplications/InternApplicationResource.php
@@ -466,7 +466,7 @@ class InternApplicationResource extends Resource
 
         $days = 0;
         while ($startDate->lte($endDate)) {
-            if (!$startDate->isWeekend()) {
+            if (!$startDate->isWeekend() && !\App\Helpers\TurkeyHolidayHelper::isHoliday($startDate)) {
                 $days++;
             }
             $startDate->addDay();
@@ -489,7 +489,7 @@ class InternApplicationResource extends Resource
         $temp = $startDate->copy();
         
         while ($count < $daysToAdd) {
-            if ($temp->isWeekend()) {
+            if ($temp->isWeekend() || \App\Helpers\TurkeyHolidayHelper::isHoliday($temp)) {
                 $temp->addDay();
                 continue;
             }
diff --git a/app/Helpers/TurkeyHolidayHelper.php b/app/Helpers/TurkeyHolidayHelper.php
new file mode 100644
index 0000000..9601936
--- /dev/null
+++ b/app/Helpers/TurkeyHolidayHelper.php
@@ -0,0 +1,84 @@
+<?php
+
+namespace App\Helpers;
+
+use Carbon\Carbon;
+
+class TurkeyHolidayHelper
+{
+    /**
+     * Checks if a given date is a national or religious holiday in Turkey.
+     *
+     * @param string|Carbon $date
+     * @return bool
+     */
+    public static function isHoliday($date): bool
+    {
+        $carbonDate = Carbon::parse($date);
+        $md = $carbonDate->format('m-d'); // Month-Day
+        $ymd = $carbonDate->format('Y-m-d'); // Year-Month-Day
+
+        // 1. Fixed Yearly Holidays
+        $fixedHolidays = [
+            '01-01', // Yılbaşı (New Year's Day)
+            '04-23', // Ulusal Egemenlik ve Çocuk Bayramı
+            '05-01', // Emek ve Dayanışma Günü
+            '05-19', // Atatürk'ü Anma, Gençlik ve Spor Bayramı
+            '07-15', // Demokrasi ve Milli Birlik Günü
+            '08-30', // Zafer Bayramı
+            '10-29', // Cumhuriyet Bayramı
+        ];
+
+        if (in_array($md, $fixedHolidays)) {
+            return true;
+        }
+
+        // 2. Variable Holidays (Ramazan & Kurban Bayramı including Eve/Arife days)
+        // Hardcoded ranges for 2024 to 2030 based on Islamic lunar calendar projections.
+        $variableHolidays = [
+            // 2024
+            '2024-04-09', // Ramazan Bayramı Arife
+            '2024-04-10', '2024-04-11', '2024-04-12', // Ramazan Bayramı
+            '2024-06-15', // Kurban Bayramı Arife
+            '2024-06-16', '2024-06-17', '2024-06-18', '2024-06-19', // Kurban Bayramı
+
+            // 2025
+            '2025-03-29', // Ramazan Bayramı Arife
+            '2025-03-30', '2025-03-31', '2025-04-01', // Ramazan Bayramı
+            '2025-06-05', // Kurban Bayramı Arife
+            '2025-06-06', '2025-06-07', '2025-06-08', '2025-06-09', // Kurban Bayramı
+
+            // 2026
+            '2026-03-19', // Ramazan Bayramı Arife
+            '2026-03-20', '2026-03-21', '2026-03-22', // Ramazan Bayramı
+            '2026-05-26', // Kurban Bayramı Arife
+            '2026-05-27', '2026-05-28', '2026-05-29', '2026-05-30', // Kurban Bayramı
+
+            // 2027
+            '2027-03-08', // Ramazan Bayramı Arife
+            '2027-03-09', '2027-03-10', '2027-03-11', // Ramazan Bayramı
+            '2027-05-15', // Kurban Bayramı Arife
+            '2027-05-16', '2027-05-17', '2027-05-18', '2027-05-19', // Kurban Bayramı
+
+            // 2028
+            '2028-02-26', // Ramazan Bayramı Arife
+            '2028-02-27', '2028-02-28', '2028-02-29', // Ramazan Bayramı
+            '2028-05-04', // Kurban Bayramı Arife
+            '2028-05-05', '2028-05-06', '2028-05-07', '2028-05-08', // Kurban Bayramı
+
+            // 2029
+            '2029-02-14', // Ramazan Bayramı Arife
+            '2029-02-15', '2029-02-16', '2029-02-17', // Ramazan Bayramı
+            '2029-04-23', // Kurban Bayramı Arife (Note: also April 23)
+            '2029-04-24', '2029-04-25', '2029-04-26', '2029-04-27', // Kurban Bayramı
+
+            // 2030
+            '2030-02-03', // Ramazan Bayramı Arife
+            '2030-02-04', '2030-02-05', '2030-02-06', // Ramazan Bayramı
+            '2030-04-12', // Kurban Bayramı Arife
+            '2030-04-13', '2030-04-14', '2030-04-15', '2030-04-16', // Kurban Bayramı
+        ];
+
+        return in_array($ymd, $variableHolidays);
+    }
+}
diff --git a/app/Http/Controllers/CareerController.php b/app/Http/Controllers/CareerController.php
index 5749b29..5c739af 100644
--- a/app/Http/Controllers/CareerController.php
+++ b/app/Http/Controllers/CareerController.php
@@ -177,7 +177,7 @@ class CareerController extends Controller
             $temp = $startDate->copy();
             
             while ($count < $daysToAdd) {
-                if ($temp->isWeekend()) {
+                if ($temp->isWeekend() || \App\Helpers\TurkeyHolidayHelper::isHoliday($temp)) {
                     $temp->addDay();
                     continue;
                 }
@@ -464,7 +464,7 @@ class CareerController extends Controller
         $count = 0;
 
         while ($count < $daysToAdd) {
-            if ($temp->isWeekend()) {
+            if ($temp->isWeekend() || \App\Helpers\TurkeyHolidayHelper::isHoliday($temp)) {
                 $temp->addDay();
                 continue;
             }
@@ -501,9 +501,9 @@ class CareerController extends Controller
             return response()->json(['success' => false, 'message' => 'İleriye dönük staj günleri için defter doldurulamaz.'], 422);
         }
 
-        // 2. Prevent weekend entries
-        if ($dateObj->isWeekend()) {
-            return response()->json(['success' => false, 'message' => 'Hafta sonu günlerine staj günlüğü girilemez.'], 422);
+        // 2. Prevent weekend and holiday entries
+        if ($dateObj->isWeekend() || \App\Helpers\TurkeyHolidayHelper::isHoliday($dateObj)) {
+            return response()->json(['success' => false, 'message' => 'Hafta sonu günlerine ve resmi tatillere staj günlüğü girilemez.'], 422);
         }
 
         // 3. Determine if retroactive
diff --git a/resources/views/front/career/intern_dashboard.blade.php b/resources/views/front/career/intern_dashboard.blade.php
index 19deb18..cb5a53d 100644
--- a/resources/views/front/career/intern_dashboard.blade.php
+++ b/resources/views/front/career/intern_dashboard.blade.php
@@ -1485,6 +1485,41 @@
     }
   }
 
+  function isTurkeyHoliday(dateObj) {
+    const yyyy = dateObj.getFullYear();
+    const mm = String(dateObj.getMonth() + 1).padStart(2, '0');
+    const dd = String(dateObj.getDate()).padStart(2, '0');
+    const ymd = `${yyyy}-${mm}-${dd}`;
+    const md = `${mm}-${dd}`;
+
+    const fixedHolidays = [
+      '01-01', '04-23', '05-01', '05-19', '07-15', '08-30', '10-29'
+    ];
+
+    if (fixedHolidays.includes(md)) {
+      return true;
+    }
+
+    const variableHolidays = [
+      '2024-04-09', '2024-04-10', '2024-04-11', '2024-04-12',
+      '2024-06-15', '2024-06-16', '2024-06-17', '2024-06-18', '2024-06-19',
+      '2025-03-29', '2025-03-30', '2025-03-31', '2025-04-01',
+      '2025-06-05', '2025-06-06', '2025-06-07', '2025-06-08', '2025-06-09',
+      '2026-03-19', '2026-03-20', '2026-03-21', '2026-03-22',
+      '2026-05-26', '2026-05-27', '2026-05-28', '2026-05-29', '2026-05-30',
+      '2027-03-08', '2027-03-09', '2027-03-10', '2027-03-11',
+      '2027-05-15', '2027-05-16', '2027-05-17', '2027-05-18', '2027-05-19',
+      '2028-02-26', '2028-02-27', '2028-02-28', '2028-02-29',
+      '2028-05-04', '2028-05-05', '2028-05-06', '2028-05-07', '2028-05-08',
+      '2029-02-14', '2029-02-15', '2029-02-16', '2029-02-17',
+      '2029-04-23', '2029-04-24', '2029-04-25', '2029-04-26', '2029-04-27',
+      '2030-02-03', '2030-02-04', '2030-02-05', '2030-02-06',
+      '2030-04-12', '2030-04-13', '2030-04-14', '2030-04-15', '2030-04-16'
+    ];
+
+    return variableHolidays.includes(ymd);
+  }
+
   function calculateEndDateFrontend() {
     const startDateVal = document.getElementById('internship_start_date').value;
     const totalDaysVal = document.getElementById('internship_total_days').value;
@@ -1501,7 +1536,7 @@
     
     while (count < daysToAdd) {
       const dayOfWeek = date.getDay();
-      if (dayOfWeek === 6 || dayOfWeek === 0) { // 6 = Saturday, 0 = Sunday
+      if (dayOfWeek === 6 || dayOfWeek === 0 || isTurkeyHoliday(date)) { // 6 = Saturday, 0 = Sunday
         date.setDate(date.getDate() + 1);
         continue;
       }