diff --git a/admin/client_prices.php b/admin/client_prices.php
index f23dd88..0b8a772 100644
--- a/admin/client_prices.php
+++ b/admin/client_prices.php
@@ -8,28 +8,36 @@ $pdo = db();
 
 $message = '';
 // Handle form submission
-if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['client_id'], $_POST['product_id'], $_POST['price'])) {
+if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['client_id'], $_POST['product_id'])) {
     $clientId = $_POST['client_id'];
     $productId = $_POST['product_id'];
-    $price = $_POST['price'];
+    $priceNet = isset($_POST['price_net']) && is_numeric($_POST['price_net']) ? (float)$_POST['price_net'] : null;
+    $priceGross = isset($_POST['price_gross']) && is_numeric($_POST['price_gross']) ? (float)$_POST['price_gross'] : null;
 
-    if (!empty($clientId) && !empty($productId) && is_numeric($price)) {
+    // Server-side validation and calculation
+    if ($priceGross !== null) {
+        $priceNet = round($priceGross / 1.23, 2);
+    } elseif ($priceNet !== null) {
+        $priceGross = round($priceNet * 1.23, 2);
+    }
+
+    if (!empty($clientId) && !empty($productId) && $priceNet !== null && $priceGross !== null) {
         // Upsert logic
         $stmt = $pdo->prepare("SELECT COUNT(*) FROM client_prices WHERE client_id = :client_id AND product_id = :product_id");
         $stmt->execute(['client_id' => $clientId, 'product_id' => $productId]);
         $exists = $stmt->fetchColumn() > 0;
 
         if ($exists) {
-            $stmt = $pdo->prepare("UPDATE client_prices SET price = :price WHERE client_id = :client_id AND product_id = :product_id");
-            $stmt->execute(['price' => $price, 'client_id' => $clientId, 'product_id' => $productId]);
+            $stmt = $pdo->prepare("UPDATE client_prices SET price_net = :price_net, price_gross = :price_gross WHERE client_id = :client_id AND product_id = :product_id");
+            $stmt->execute(['price_net' => $priceNet, 'price_gross' => $priceGross, 'client_id' => $clientId, 'product_id' => $productId]);
             $message = '<div class="alert alert-success">Cena została zaktualizowana.</div>';
         } else {
-            $stmt = $pdo->prepare("INSERT INTO client_prices (client_id, product_id, price) VALUES (:client_id, :product_id, :price)");
-            $stmt->execute(['client_id' => $clientId, 'product_id' => $productId, 'price' => $price]);
+            $stmt = $pdo->prepare("INSERT INTO client_prices (client_id, product_id, price_net, price_gross) VALUES (:client_id, :product_id, :price_net, :price_gross)");
+            $stmt->execute(['client_id' => $clientId, 'product_id' => $productId, 'price_net' => $priceNet, 'price_gross' => $priceGross]);
             $message = '<div class="alert alert-success">Nowa cena została dodana.</div>';
         }
     } else {
-        $message = '<div class="alert alert-danger">Wszystkie pola są wymagane.</div>';
+        $message = '<div class="alert alert-danger">Wszystkie pola są wymagane, a ceny muszą być prawidłowymi liczbami.</div>';
     }
 }
 
@@ -42,7 +50,8 @@ $pricesStmt = $pdo->query("
     SELECT
         cp.client_id,
         cp.product_id,
-        cp.price,
+        cp.price_net,
+        cp.price_gross,
         c.name as client_name,
         p.name as product_name
     FROM client_prices cp
@@ -80,7 +89,7 @@ $existingPrices = $pricesStmt->fetchAll(PDO::FETCH_ASSOC);
                     <div class="card-body">
                         <form method="POST" action="client_prices.php">
                             <div class="row">
-                                <div class="col-md-4 mb-3">
+                                <div class="col-md-3 mb-3">
                                     <label for="client_id" class="form-label">Klient:</label>
                                     <select name="client_id" id="client_id" class="form-select" required>
                                         <option value="">Wybierz klienta</option>
@@ -89,7 +98,7 @@ $existingPrices = $pricesStmt->fetchAll(PDO::FETCH_ASSOC);
                                         <?php endforeach; ?>
                                     </select>
                                 </div>
-                                <div class="col-md-4 mb-3">
+                                <div class="col-md-3 mb-3">
                                     <label for="product_id" class="form-label">Produkt:</label>
                                     <select name="product_id" id="product_id" class="form-select" required>
                                         <option value="">Wybierz produkt</option>
@@ -99,8 +108,12 @@ $existingPrices = $pricesStmt->fetchAll(PDO::FETCH_ASSOC);
                                     </select>
                                 </div>
                                 <div class="col-md-2 mb-3">
-                                    <label for="price" class="form-label">Cena:</label>
-                                    <input type="number" step="0.01" name="price" id="price" class="form-control" required>
+                                    <label for="price_net" class="form-label">Cena netto (PLN):</label>
+                                    <input type="number" step="0.01" name="price_net" id="price_net" class="form-control">
+                                </div>
+                                <div class="col-md-2 mb-3">
+                                    <label for="price_gross" class="form-label">Cena brutto (PLN):</label>
+                                    <input type="number" step="0.01" name="price_gross" id="price_gross" class="form-control">
                                 </div>
                                 <div class="col-md-2 d-flex align-items-end">
                                     <button type="submit" class="btn btn-primary w-100">Zapisz</button>
@@ -117,20 +130,22 @@ $existingPrices = $pricesStmt->fetchAll(PDO::FETCH_ASSOC);
                             <tr>
                                 <th>Klient</th>
                                 <th>Produkt</th>
-                                <th>Cena (PLN)</th>
+                                <th>Cena netto (PLN)</th>
+                                <th>Cena brutto (PLN)</th>
                             </tr>
                         </thead>
                         <tbody>
                             <?php if (empty($existingPrices)): ?>
                                 <tr>
-                                    <td colspan="3" class="text-center">Brak zdefiniowanych cen indywidualnych.</td>
+                                    <td colspan="4" class="text-center">Brak zdefiniowanych cen indywidualnych.</td>
                                 </tr>
                             <?php else: ?>
                                 <?php foreach ($existingPrices as $price): ?>
                                     <tr>
                                         <td><?php echo htmlspecialchars($price['client_name']); ?></td>
                                         <td><?php echo htmlspecialchars($price['product_name']); ?></td>
-                                        <td><?php echo number_format($price['price'], 2, ',', ' '); ?></td>
+                                        <td><?php echo number_format($price['price_net'], 2, ',', ' '); ?></td>
+                                        <td><?php echo number_format($price['price_gross'], 2, ',', ' '); ?></td>
                                     </tr>
                                 <?php endforeach; ?>
                             <?php endif; ?>
@@ -141,4 +156,30 @@ $existingPrices = $pricesStmt->fetchAll(PDO::FETCH_ASSOC);
         </div>
     </div>
 
+    <script>
+        document.addEventListener('DOMContentLoaded', function () {
+            const priceNetInput = document.getElementById('price_net');
+            const priceGrossInput = document.getElementById('price_gross');
+            const vatRate = 1.23;
+
+            priceNetInput.addEventListener('input', function () {
+                const netValue = parseFloat(this.value);
+                if (!isNaN(netValue)) {
+                    priceGrossInput.value = (netValue * vatRate).toFixed(2);
+                } else {
+                    priceGrossInput.value = '';
+                }
+            });
+
+            priceGrossInput.addEventListener('input', function () {
+                const grossValue = parseFloat(this.value);
+                if (!isNaN(grossValue)) {
+                    priceNetInput.value = (grossValue / vatRate).toFixed(2);
+                } else {
+                    priceNetInput.value = '';
+                }
+            });
+        });
+    </script>
+
 <?php include __DIR__ . '/../includes/footer.php'; ?>
\ No newline at end of file
diff --git a/admin/edit_client.php b/admin/edit_client.php
index 6d39124..6d76e26 100644
--- a/admin/edit_client.php
+++ b/admin/edit_client.php
@@ -1,8 +1,8 @@
 <?php
+session_start();
 require_once __DIR__ . '/../includes/auth.php';
 require_role('admin');
 require_once __DIR__ . '/../includes/helpers.php';
-require_once __DIR__ . '/menu.php';
 
 $db = db();
 
@@ -92,6 +92,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
     <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet">
 </head>
 <body>
+<?php require_once __DIR__ . '/menu.php'; ?>
 <div class="container mt-4">
     <div class="card">
         <div class="card-header">
diff --git a/admin/order_details.php b/admin/order_details.php
index 55d5ad4..b0129b1 100644
--- a/admin/order_details.php
+++ b/admin/order_details.php
@@ -99,16 +99,23 @@ $pageTitle = 'Szczegóły zamówienia #' . htmlspecialchars($order['id']);
                                 <tr>
                                     <th>Produkt</th>
                                     <th>Ilość</th>
-                                    <th>Cena jednostkowa</th>
-                                    <th>Suma</th>
+                                    <th>Cena jedn. netto</th>
+                                    <th>Cena jedn. brutto</th>
+                                    <th>Suma (brutto)</th>
                                 </tr>
                             </thead>
                             <tbody>
-                                <?php foreach ($order_items as $item): ?>
+                                <?php 
+                                $vatRate = 1.23;
+                                foreach ($order_items as $item): 
+                                    $unit_price_gross = (float)$item['unit_price'];
+                                    $unit_price_net = $unit_price_gross / $vatRate;
+                                ?>
                                 <tr>
                                     <td><?php echo htmlspecialchars($item['product_name']); ?></td>
                                     <td><?php echo htmlspecialchars($item['quantity']); ?></td>
-                                    <td><?php echo number_format($item['unit_price'], 2, ',', ' '); ?> zł</td>
+                                    <td><?php echo number_format($unit_price_net, 2, ',', ' '); ?> zł</td>
+                                    <td><?php echo number_format($unit_price_gross, 2, ',', ' '); ?> zł</td>
                                     <td><?php echo number_format($item['line_total'], 2, ',', ' '); ?> zł</td>
                                 </tr>
                                 <?php endforeach; ?>
@@ -125,7 +132,7 @@ $pageTitle = 'Szczegóły zamówienia #' . htmlspecialchars($order['id']);
                     <p><strong>Klient:</strong> <?php echo htmlspecialchars($order['client_company_name'] ?? 'Brak'); ?></p>
                     <p><strong>Data:</strong> <?php echo date('d.m.Y H:i', strtotime($order['created_at'])); ?></p>
                     <p><strong>Metoda płatności:</strong> <span class="badge bg-secondary"><?php echo htmlspecialchars(get_payment_method_translation_local($order['payment_method'], $i18n)); ?></span></p>
-                    <p><strong>Suma:</strong> <strong class="fs-5"><?php echo number_format($order['total_amount'], 2, ',', ' '); ?> zł</strong></p>
+                    <p><strong>Suma (brutto):</strong> <strong class="fs-5"><?php echo number_format($order['total_amount'], 2, ',', ' '); ?> zł</strong></p>
                 </div>
             </div>
             <div class="card">
diff --git a/admin/orders.php b/admin/orders.php
index 4659330..d3da23a 100644
--- a/admin/orders.php
+++ b/admin/orders.php
@@ -125,7 +125,7 @@ $pageTitle = "Zarządzanie zamówieniami";
                         <th>Data</th>
                         <th>Status</th>
                         <th>Źródło</th>
-                        <th>Suma</th>
+                        <th>Suma (brutto)</th>
                         <th>Akcje</th>
                     </tr>
                 </thead>
diff --git a/cart.php b/cart.php
index 6f55f12..65729bb 100644
--- a/cart.php
+++ b/cart.php
@@ -18,38 +18,32 @@ if (!empty($cart)) {
 
     try {
         $pdo = db();
-        
         $client_id = $_SESSION['client_id'] ?? null;
-        $params = [];
 
-        $sql = 'SELECT p.*, ';
-        if ($client_id) {
-            $sql .= 'COALESCE(cp.price, p.price) as final_price FROM products p';
-            $sql .= ' LEFT JOIN client_prices cp ON p.id = cp.product_id AND cp.client_id = ?';
-            $params[] = $client_id;
-        } else {
-            $sql .= 'p.price as final_price FROM products p';
-        }
-
-        $sql .= " WHERE p.id IN ($placeholders)";
-        
-        $params = array_merge($params, $product_ids);
-
-        $stmt = $pdo->prepare($sql);
-        $stmt->execute($params);
+        $stmt = $pdo->prepare("SELECT * FROM products WHERE id IN ($placeholders)");
+        $stmt->execute($product_ids);
         $products = $stmt->fetchAll(PDO::FETCH_ASSOC);
 
         foreach ($products as $product) {
             $quantity = $cart[$product['id']];
-            $line_total = $product['final_price'] * $quantity;
+            
+            // Use the new centralized price function
+            $price_info = getEffectivePrice($pdo, $product['id'], $client_id);
+            $price_net = $price_info['net'];
+            $price_gross = $price_info['gross'];
+
+            $line_total_gross = $price_gross * $quantity;
+
             $cart_products[] = [
                 'id' => $product['id'],
                 'name' => $product['name'],
-                'price' => $product['final_price'],
+                'price_net' => $price_net,
+                'price_gross' => $price_gross,
                 'quantity' => $quantity,
-                'line_total' => $line_total,
+                'line_total' => $line_total_gross, // Use gross for calculations
             ];
-            $total_price += $line_total;
+            
+            $total_price += $line_total_gross; // Sum up the gross total
         }
     } catch (PDOException $e) {
         die("Błąd połączenia z bazą danych: " . $e->getMessage());
@@ -126,7 +120,8 @@ $user_role = get_user_role();
                 <thead>
                     <tr>
                         <th>Produkt</th>
-                        <th>Cena</th>
+                        <th>Cena netto</th>
+                        <th>Cena brutto</th>
                         <th>Ilość</th>
                         <th>Razem</th>
                         <th></th>
@@ -136,7 +131,8 @@ $user_role = get_user_role();
                     <?php foreach ($cart_products as $item): ?>
                         <tr>
                             <td><?php echo htmlspecialchars($item['name']); ?></td>
-                            <td><?php echo number_format($item['price'], 2, ',', ' '); ?> zł</td>
+                            <td><?php echo number_format($item['price_net'], 2, ',', ' '); ?> zł</td>
+                            <td><?php echo number_format($item['price_gross'], 2, ',', ' '); ?> zł</td>
                             <td>
                                 <form action="cart_actions.php" method="POST" class="d-inline-flex align-items-center">
                                     <input type="hidden" name="action" value="update">
@@ -161,7 +157,7 @@ $user_role = get_user_role();
                 </tbody>
                 <tfoot>
                     <tr>
-                        <td colspan="3" class="text-end"><strong>Razem:</strong></td>
+                        <td colspan="4" class="text-end"><strong>Razem (brutto):</strong></td>
                         <td colspan="2"><strong><?php echo number_format($total_price, 2, ',', ' '); ?> zł</strong></td>
                     </tr>
                 </tfoot>
diff --git a/checkout.php b/checkout.php
index 98a8ac1..1718a65 100644
--- a/checkout.php
+++ b/checkout.php
@@ -30,20 +30,25 @@ if (!empty($cart)) {
             $credit_info = $stmt->fetch(PDO::FETCH_ASSOC);
         }
 
-        $sql = "SELECT p.id, p.name, p.units_per_pallet, COALESCE(cp.price, p.price_gross) as price FROM products p LEFT JOIN client_prices cp ON p.id = cp.product_id AND cp.client_id = ? WHERE p.id IN ($placeholders)";
+        $sql = "SELECT p.id, p.name, p.units_per_pallet FROM products p WHERE p.id IN ($placeholders)";
         $stmt = $pdo->prepare($sql);
-        $params = array_merge([$client_id], $product_ids);
-        $stmt->execute($params);
+        $stmt->execute($product_ids);
         $products = $stmt->fetchAll(PDO::FETCH_ASSOC);
 
         $is_supplier_delivery = false;
         foreach ($products as $product) {
             $quantity = $cart[$product['id']];
-            $line_total = $product['price'] * $quantity;
+
+            $price_info = getEffectivePrice($pdo, $product['id'], $client_id);
+            $price_net = $price_info['net'];
+            $price_gross = $price_info['gross'];
+
+            $line_total = $price_gross * $quantity;
             $cart_products[] = [
                 'id' => $product['id'],
                 'name' => $product['name'],
-                'price' => $product['price'],
+                'price_net' => $price_net,
+                'price_gross' => $price_gross,
                 'quantity' => $quantity,
                 'line_total' => $line_total,
             ];
@@ -134,8 +139,9 @@ $user_role = get_user_role();
                                 <tr>
                                     <th>Produkt</th>
                                     <th>Ilość</th>
-                                    <th>Cena jedn.</th>
-                                    <th>Suma</th>
+                                    <th>Cena netto</th>
+                                    <th>Cena brutto</th>
+                                    <th>Suma (brutto)</th>
                                 </tr>
                             </thead>
                             <tbody>
@@ -143,14 +149,15 @@ $user_role = get_user_role();
                                     <tr>
                                         <td><?php echo htmlspecialchars($item['name']); ?></td>
                                         <td><?php echo $item['quantity']; ?></td>
-                                        <td><?php echo number_format($item['price'], 2, ',', ' '); ?> zł</td>
+                                        <td><?php echo number_format($item['price_net'], 2, ',', ' '); ?> zł</td>
+                                        <td><?php echo number_format($item['price_gross'], 2, ',', ' '); ?> zł</td>
                                         <td><?php echo number_format($item['line_total'], 2, ',', ' '); ?> zł</td>
                                     </tr>
                                 <?php endforeach; ?>
                             </tbody>
                             <tfoot>
                                 <tr>
-                                    <td colspan="3" class="text-end"><strong>Suma:</strong></td>
+                                    <td colspan="4" class="text-end"><strong>Suma (brutto):</strong></td>
                                     <td><strong><?php echo number_format($total_price, 2, ',', ' '); ?> zł</strong></td>
                                 </tr>
                             </tfoot>
diff --git a/db/migrations/026_add_net_gross_to_client_prices.sql b/db/migrations/026_add_net_gross_to_client_prices.sql
new file mode 100644
index 0000000..c23ca45
--- /dev/null
+++ b/db/migrations/026_add_net_gross_to_client_prices.sql
@@ -0,0 +1,10 @@
+-- Add net and gross price columns to client_prices
+ALTER TABLE client_prices
+ADD COLUMN price_net DECIMAL(10, 2) NULL,
+ADD COLUMN price_gross DECIMAL(10, 2) NULL;
+
+-- Migrate existing price to price_gross (assuming it was gross)
+UPDATE client_prices SET price_gross = price WHERE price IS NOT NULL;
+
+-- Calculate price_net from price_gross
+UPDATE client_prices SET price_net = ROUND(price_gross / 1.23, 2) WHERE price_gross IS NOT NULL;
diff --git a/includes/helpers.php b/includes/helpers.php
index 991ce5a..1022e70 100644
--- a/includes/helpers.php
+++ b/includes/helpers.php
@@ -75,3 +75,58 @@ function upload_error_message($error_code) {
             return 'Unknown upload error';
     }
 }
+
+function getEffectivePrice(PDO $db, int $productId, ?int $clientId): array {
+    $vatRate = 1.23;
+    $net = null;
+    $gross = null;
+    $priceFound = false;
+
+    // Priority A: Try to fetch from client_prices
+    if ($clientId) {
+        $stmt = $db->prepare("SELECT price_net, price_gross FROM client_prices WHERE client_id = :client_id AND product_id = :product_id LIMIT 1");
+        $stmt->execute(['client_id' => $clientId, 'product_id' => $productId]);
+        $priceRow = $stmt->fetch(PDO::FETCH_ASSOC);
+
+        if ($priceRow) {
+            $net = $priceRow['price_net'] !== null ? (float)$priceRow['price_net'] : null;
+            $gross = $priceRow['price_gross'] !== null ? (float)$priceRow['price_gross'] : null;
+
+            if ($net !== null || $gross !== null) {
+                $priceFound = true;
+            }
+        }
+    }
+
+    // Priority B: Fallback to product base prices if no client-specific price was found
+    if (!$priceFound) {
+        $stmt = $db->prepare("SELECT price_net, price_gross FROM products WHERE id = :product_id");
+        $stmt->execute(['product_id' => $productId]);
+        $priceRow = $stmt->fetch(PDO::FETCH_ASSOC);
+
+        if ($priceRow) {
+            $net = $priceRow['price_net'] !== null ? (float)$priceRow['price_net'] : null;
+            $gross = $priceRow['price_gross'] !== null ? (float)$priceRow['price_gross'] : null;
+        }
+    }
+
+    // If we have one price, calculate the other
+    if ($gross !== null && $net === null) {
+        $net = round($gross / $vatRate, 2);
+    } elseif ($net !== null && $gross === null) {
+        $gross = round($net * $vatRate, 2);
+    }
+
+    // Sanity check: gross must not be less than net. If so, log it and fix it.
+    if ($gross !== null && $net !== null && $gross < $net) {
+        error_log("Price inconsistency for product ID $productId: gross ($gross) is less than net ($net). Recalculating net from gross.");
+        $net = round($gross / $vatRate, 2);
+    }
+    
+    // Final check for nulls before returning
+    if ($net === null || $gross === null) {
+        return ['net' => 0.0, 'gross' => 0.0];
+    }
+
+    return ['net' => $net, 'gross' => $gross];
+}
diff --git a/index.php b/index.php
index 66bb697..0b5f6e3 100644
--- a/index.php
+++ b/index.php
@@ -11,9 +11,7 @@ try {
     
     // Fetch products and their primary images
     $sql = "SELECT 
-                p.*, 
-                COALESCE(cp.price, p.price_gross) as final_price,
-                p.price_net as final_price_net,
+                p.*,
                 (SELECT file_path 
                  FROM product_images 
                  WHERE product_id = p.id 
@@ -21,17 +19,13 @@ try {
                  LIMIT 1) AS image_path
             FROM 
                 products p
-            LEFT JOIN 
-                users u ON u.id = :user_id
-            LEFT JOIN 
-                client_prices cp ON cp.product_id = p.id AND cp.client_id = u.client_id
             WHERE 
                 p.is_active = 1
             ORDER BY 
                 CASE p.product_role WHEN 'membrana' THEN 1 WHEN 'akcesoria' THEN 2 ELSE 3 END, p.name ASC";
 
     $stmt = $pdo->prepare($sql);
-    $stmt->execute(['user_id' => $_SESSION['user_id']]);
+    $stmt->execute();
     $products = $stmt->fetchAll(PDO::FETCH_ASSOC);
 
     // Separate products into main and accessories
@@ -132,7 +126,8 @@ $page_title = 'Katalog';
         <?php endif; ?>
 
         <div class="row row-cols-1 row-cols-sm-2 row-cols-md-3 row-cols-lg-4 g-4">
-            <?php foreach ($main_products as $product):
+            <?php foreach ($main_products as $product): 
+                $prices = getEffectivePrice($pdo, $product['id'], $_SESSION['client_id']);
                 $image_url = !empty($product['image_path'])
                     ? 'uploads/products/' . htmlspecialchars($product['image_path'])
                     : 'https://placehold.co/600x400/EEE/31343C?text=Brak+zdj%C4%99cia';
@@ -152,7 +147,10 @@ $page_title = 'Katalog';
                                 $desc = $product['description'];
                                 echo htmlspecialchars(strlen($desc) > 100 ? substr($desc, 0, 100) . '...' : $desc);
                             ?></p>
-                            <p class="card-text fw-bold fs-5 mt-auto"><?= htmlspecialchars(number_format($product['final_price'], 2, ',', ' ')) ?> PLN / <?= htmlspecialchars($product['unit']) ?></p>
+                            <div class="mt-auto">
+                                <p class="card-text text-muted small mb-0"><?= htmlspecialchars(number_format($prices['net'], 2, ',', ' ')) ?> zł netto</p>
+                                <p class="card-text fw-bold fs-5"><?= htmlspecialchars(number_format($prices['gross'], 2, ',', ' ')) ?> zł brutto</p>
+                            </div>
                         </div>
                         <div class="card-footer bg-white border-top-0 pb-3">
                              <form action="cart_actions.php" method="POST" class="d-grid">
@@ -177,6 +175,7 @@ $page_title = 'Katalog';
             <h2 class="mb-4">Akcesoria i produkty uzupełniające</h2>
             <div class="row row-cols-1 row-cols-sm-2 row-cols-md-4 row-cols-lg-5 g-4">
                 <?php foreach ($accessories as $product):
+                    $prices = getEffectivePrice($pdo, $product['id'], $_SESSION['client_id']);
                     $image_url = !empty($product['image_path'])
                         ? 'uploads/products/' . htmlspecialchars($product['image_path'])
                         : 'https://placehold.co/600x400/EEE/31343C?text=Brak+zdj%C4%99cia';
@@ -192,7 +191,10 @@ $page_title = 'Katalog';
                                         <?= htmlspecialchars($product['name']) ?>
                                     </a>
                                 </h6>
-                                <p class="card-text fw-bold mt-auto"><?= htmlspecialchars(number_format($product['final_price'], 2, ',', ' ')) ?> PLN / <?= htmlspecialchars($product['unit']) ?></p>
+                                <div class="mt-auto">
+                                    <p class="card-text text-muted small mb-0"><?= htmlspecialchars(number_format($prices['net'], 2, ',', ' ')) ?> zł netto</p>
+                                    <p class="card-text fw-bold"><?= htmlspecialchars(number_format($prices['gross'], 2, ',', ' ')) ?> zł brutto</p>
+                                </div>
                             </div>
                             <div class="card-footer bg-white border-top-0 pb-3">
                                  <form action="cart_actions.php" method="POST" class="d-grid">
diff --git a/order_details.php b/order_details.php
index 644c6fe..2c0db8f 100644
--- a/order_details.php
+++ b/order_details.php
@@ -161,7 +161,7 @@ $lang = 'pl';
                     <p><strong>Data zamówienia:</strong> <?php echo date('d.m.Y H:i', strtotime($order['created_at'])); ?></p>
                     <p><strong>Status:</strong> <span class="badge bg-info"><?php echo htmlspecialchars(get_polish_status_translation($order['status'])); ?></span></p>
                     <p><strong>Metoda płatności:</strong> <?php echo htmlspecialchars(get_polish_status_translation($order['payment_method'])); ?></p>
-                    <p><strong>Suma:</strong> <?php echo number_format($order['total_amount'], 2, ',', ' '); ?> zł</p>
+                    <p><strong>Suma (brutto):</strong> <?php echo number_format($order['total_amount'], 2, ',', ' '); ?> zł</p>
                     <p><strong>Uwagi:</strong> <?php echo nl2br(htmlspecialchars($order['notes'])); ?></p>
                 </div>
             </div>
@@ -174,19 +174,25 @@ $lang = 'pl';
                             <tr>
                                 <th>Zdjęcie</th>
                                 <th>Produkt</th>
-                                <th>Cena jednostkowa</th>
+                                <th>Cena jedn. netto</th>
+                                <th>Cena jedn. brutto</th>
                                 <th>Ilość</th>
-                                <th>Suma częściowa</th>
+                                <th>Suma (brutto)</th>
                             </tr>
                         </thead>
                         <tbody>
-                            <?php foreach ($order_items as $item): 
+                            <?php 
+                            $vatRate = 1.23;
+                            foreach ($order_items as $item): 
                                 $image_url = $product_images[$item['product_id']] ?? 'https://placehold.co/100x100/EEE/31343C?text=' . urlencode('Brak zdjęcia');
+                                $unit_price_gross = (float)$item['unit_price'];
+                                $unit_price_net = $unit_price_gross / $vatRate;
                             ?>
                                 <tr>
                                     <td><img src="<?php echo htmlspecialchars($image_url); ?>" alt="<?php echo htmlspecialchars($item['product_name']); ?>" style="width: 50px; height: 50px; object-fit: cover;"></td>
                                     <td><?php echo htmlspecialchars($item['product_name']); ?></td>
-                                    <td><?php echo number_format($item['unit_price'], 2, ',', ' '); ?> zł</td>
+                                    <td><?php echo number_format($unit_price_net, 2, ',', ' '); ?> zł</td>
+                                    <td><?php echo number_format($unit_price_gross, 2, ',', ' '); ?> zł</td>
                                     <td><?php echo $item['quantity']; ?></td>
                                     <td><?php echo number_format($item['line_total'], 2, ',', ' '); ?> zł</td>
                                 </tr>
diff --git a/order_process.php b/order_process.php
index 18f55e3..5b5b15c 100644
--- a/order_process.php
+++ b/order_process.php
@@ -31,27 +31,28 @@ try {
     $products_by_id = $stmt->fetchAll(PDO::FETCH_GROUP|PDO::FETCH_UNIQUE|PDO::FETCH_ASSOC);
 
 
-    // 2. Calculate total amount & total pallets
-    $total_amount = 0;
-    $is_supplier_delivery = false;
+    // 2. Calculate total amount
+    $total_amount_gross = 0;
     $client_id = $_SESSION['client_id'] ?? null;
     
-    $product_prices = [];
-    if ($client_id) {
-        $price_placeholders = implode(',', array_fill(0, count($product_ids), '?'));
-        $sql = "SELECT p.id, COALESCE(cp.price, p.price) as price FROM products p LEFT JOIN client_prices cp ON p.id = cp.product_id AND cp.client_id = ? WHERE p.id IN ($price_placeholders)";
-        $stmt = $pdo->prepare($sql);
-        $params = array_merge([$client_id], $product_ids);
-        $stmt->execute($params);
-        $product_prices = $stmt->fetchAll(PDO::FETCH_KEY_PAIR);
-    }
+    $order_items_data = [];
 
     $is_supplier_delivery = false;
     foreach ($cart as $product_id => $quantity) {
         if (isset($products_by_id[$product_id])) {
             $product = $products_by_id[$product_id];
-            $price = $product_prices[$product_id] ?? $product['price'];
-            $total_amount += $price * $quantity;
+            
+            $price_info = getEffectivePrice($pdo, $product_id, $client_id);
+            $price_gross = $price_info['gross'];
+
+            $total_amount_gross += $price_gross * $quantity;
+
+            $order_items_data[] = [
+                'product_id' => $product_id,
+                'quantity' => $quantity,
+                'unit_price' => $price_gross, // Save gross price
+                'line_total' => $price_gross * $quantity,
+            ];
 
             $units_per_pallet = $product['units_per_pallet'];
             if (isset($units_per_pallet) && $units_per_pallet > 0) {
@@ -69,11 +70,11 @@ try {
         $stmt->execute([$client_id]);
         $credit_info = $stmt->fetch();
 
-        if (!$credit_info || !$credit_info['credit_enabled'] || $credit_info['credit_balance'] < $total_amount) {
+        if (!$credit_info || !$credit_info['credit_enabled'] || $credit_info['credit_balance'] < $total_amount_gross) {
             throw new Exception('Invalid payment method or insufficient credit.');
         }
 
-        $new_balance = $credit_info['credit_balance'] - $total_amount;
+        $new_balance = $credit_info['credit_balance'] - $total_amount_gross;
         $stmt = $pdo->prepare('UPDATE clients SET credit_balance = ? WHERE id = ?');
         $stmt->execute([$new_balance, $client_id]);
     }
@@ -84,7 +85,7 @@ try {
     );
     $stmt->execute([
         $client_id,
-        $total_amount,
+        $total_amount_gross,
         $_POST['payment_method'],
         $delivery_source,
         $_POST['notes'],
@@ -96,18 +97,14 @@ try {
     $stmt = $pdo->prepare(
         'INSERT INTO order_items (order_id, product_id, quantity, unit_price, line_total) VALUES (?, ?, ?, ?, ?)'
     );
-    foreach ($cart as $product_id => $quantity) {
-        if (isset($products_by_id[$product_id])) {
-            $product = $products_by_id[$product_id];
-            $price = $product_prices[$product_id] ?? $product['price'];
-            $stmt->execute([
-                $order_id,
-                $product_id,
-                $quantity,
-                $price,
-                $price * $quantity
-            ]);
-        }
+    foreach ($order_items_data as $item) {
+        $stmt->execute([
+            $order_id,
+            $item['product_id'],
+            $item['quantity'],
+            $item['unit_price'],
+            $item['line_total'],
+        ]);
     }
 
     // 5. Commit the transaction
diff --git a/orders.php b/orders.php
index 5a3e5e7..e5608f9 100644
--- a/orders.php
+++ b/orders.php
@@ -126,7 +126,7 @@ $lang = 'pl';
                         <th>Numer zamówienia</th>
                         <th>Data zamówienia</th>
                         <th>Status</th>
-                        <th>Suma</th>
+                        <th>Suma (brutto)</th>
                         <th></th>
                     </tr>
                 </thead>
diff --git a/product.php b/product.php
index c118734..726ddf7 100644
--- a/product.php
+++ b/product.php
@@ -15,25 +15,17 @@ if (!$product_id) {
 
 try {
     $pdo = db();
-    $stmt = $pdo->prepare("SELECT p.*, 
-                                 COALESCE(cp.price, p.price_gross) as final_price,
-                                 p.price_net as final_price_net
-                             FROM products p
-                             LEFT JOIN users u ON u.id = :user_id
-                             LEFT JOIN client_prices cp ON cp.product_id = p.id AND cp.client_id = u.client_id
-                             WHERE p.id = :product_id");
-    $stmt->execute(['user_id' => $_SESSION['user_id'], 'product_id' => $product_id]);
+    $stmt = $pdo->prepare("SELECT p.* FROM products p WHERE p.id = :product_id");
+    $stmt->execute(['product_id' => $product_id]);
     $product = $stmt->fetch(PDO::FETCH_ASSOC);
 
     if (!$product) {
         header('Location: index.php');
         exit;
     }
-    
-    // If client-specific price is used, re-calculate net price from it
-    if (!empty($product['final_price']) && empty($product['final_price_net'])) {
-        $product['final_price_net'] = round($product['final_price'] / 1.23, 2);
-    }
+
+    // Get the correct price pair using the centralized function
+    $prices = getEffectivePrice($pdo, $product['id'], $_SESSION['client_id']);
 
 
     // Fetch product images
@@ -139,9 +131,10 @@ $user_role = get_user_role();
                 <h1 class="mb-3"><?= htmlspecialchars($product['name']) ?></h1>
                 
                 <div class="bg-light p-4 rounded mb-4">
-                    <h2 class="h4 fw-bold"><?= htmlspecialchars(number_format($product['final_price'], 2, ',', ' ')) ?> PLN / <?= htmlspecialchars($product['unit']) ?></h2>
-                    <small class="text-muted">Cena brutto</small>
-                    <p class="mb-0"><?= htmlspecialchars(number_format($product['final_price_net'], 2, ',', ' ')) ?> PLN netto</p>
+                    <p class="h4 fw-bold mb-1"><?= htmlspecialchars(number_format($prices['gross'], 2, ',', ' ')) ?> zł <span class="fs-6 fw-normal">brutto</span></p>
+                    <p class="text-muted mb-0"><?= htmlspecialchars(number_format($prices['net'], 2, ',', ' ')) ?> zł <span class="fs-6 fw-normal">netto</span></p>
+                    <hr class="my-2">
+                    <small class="text-muted">Cena za: <?= htmlspecialchars($product['unit']) ?></small>
                 </div>
 
                 <form action="cart_actions.php" method="post" class="d-flex align-items-center">
diff --git a/related_suggestions.php b/related_suggestions.php
index a295242..2ca49a2 100644
--- a/related_suggestions.php
+++ b/related_suggestions.php
@@ -27,15 +27,13 @@ $stmt = $db->prepare("
         p.name, 
         p.unit, 
         p.price_net,
-        COALESCE(cp.price, p.price_gross) as final_price, 
+        p.price_gross, 
         pi.file_path AS primary_image
     FROM products p 
-    LEFT JOIN users u ON u.id = :user_id
-    LEFT JOIN client_prices cp ON cp.product_id = p.id AND cp.client_id = u.client_id
     LEFT JOIN product_images pi ON pi.product_id = p.id AND pi.is_primary = 1
     WHERE p.id = :product_id
 ");
-$stmt->execute(['user_id' => $user_id, 'product_id' => $product_id]);
+$stmt->execute(['product_id' => $product_id]);
 $added_product = $stmt->fetch(PDO::FETCH_ASSOC);
 
 // If product somehow doesn't exist, redirect away
@@ -43,6 +41,8 @@ if (!$added_product) {
     header('Location: cart.php');
     exit;
 }
+$added_product_price = getEffectivePrice($db, $added_product['id'], $_SESSION['client_id'] ?? null);
+
 
 // If image is not found, use a placeholder
 if (empty($added_product['primary_image'])) {
@@ -57,16 +57,14 @@ $related_products_stmt = $db->prepare("
         p.name,
         p.unit,
         p.price_net,
-        COALESCE(cp.price, p.price_gross) as final_price,
+        p.price_gross,
         pi.file_path as primary_image
     FROM products p
     JOIN product_relations pr ON p.id = pr.related_product_id
-    LEFT JOIN users u ON u.id = :user_id
-    LEFT JOIN client_prices cp ON cp.product_id = p.id AND cp.client_id = u.client_id
     LEFT JOIN product_images pi ON p.id = pi.product_id AND pi.is_primary = 1
     WHERE pr.product_id = :product_id AND p.product_role = 'akcesoria'
 ");
-$related_products_stmt->execute(['user_id' => $user_id, 'product_id' => $product_id]);
+$related_products_stmt->execute(['product_id' => $product_id]);
 $related_products = $related_products_stmt->fetchAll(PDO::FETCH_ASSOC);
 
 $user_role = get_user_role();
@@ -165,8 +163,8 @@ $page_title = 'Dodano do koszyka';
                 <div class="col-md-5">
                     <div class="d-flex justify-content-end align-items-center">
                         <div class="text-end">
-                            <p class="mb-0 h5"><strong><?= number_format($added_product['final_price'], 2, ',', ' '); ?> zł</strong> <small>brutto</small></p>
-                            <p class="mb-0 text-muted"><?= number_format($added_product['price_net'], 2, ',', ' '); ?> zł <small>netto</small></p>
+                            <p class="mb-0 h5"><strong><?= number_format($added_product_price['gross'], 2, ',', ' '); ?> zł</strong> <small>brutto</small></p>
+                            <p class="mb-0 text-muted"><?= number_format($added_product_price['net'], 2, ',', ' '); ?> zł <small>netto</small></p>
                         </div>
                     </div>
                 </div>
@@ -178,7 +176,9 @@ $page_title = 'Dodano do koszyka';
     <?php if (!empty($related_products)): ?>
         <h3 class="mt-5 mb-4">Polecamy także produkty powiązane:</h3>
         <div class="list-group">
-            <?php foreach ($related_products as $product): ?>
+            <?php foreach ($related_products as $product): 
+                $effective_price = getEffectivePrice($db, $product['id'], $_SESSION['client_id'] ?? null);
+            ?>
                 <div class="list-group-item list-group-item-action">
                     <div class="row align-items-center">
                         <div class="col-md-2 text-center">
@@ -198,8 +198,8 @@ $page_title = 'Dodano do koszyka';
                         </div>
                         <div class="col-md-3">
                             <div class="text-end">
-                                <p class="mb-0 h5"><strong><?= number_format($product['final_price'], 2, ',', ' '); ?> zł</strong> <small>brutto</small></p>
-                                <p class="mb-0 text-muted"><?= number_format($product['price_net'], 2, ',', ' '); ?> zł <small>netto</small></p>
+                                <p class="mb-0 h5"><strong><?= number_format($effective_price['gross'], 2, ',', ' '); ?> zł</strong> <small>brutto</small></p>
+                                <p class="mb-0 text-muted"><?= number_format($effective_price['net'], 2, ',', ' '); ?> zł <small>netto</small></p>
                             </div>
                         </div>
                         <div class="col-md-3">