diff --git a/customers/.hta_slug/generate-invoice.php b/customers/.hta_slug/generate-invoice.php
index ad93e76..0410024 100644
--- a/customers/.hta_slug/generate-invoice.php
+++ b/customers/.hta_slug/generate-invoice.php
@@ -105,7 +105,11 @@
 
             $stmt = $db->query("SELECT id FROM invoice WHERE DATE(invoiceDate) = CURDATE() ORDER BY id DESC LIMIT 1");
             $lastInvoice = $stmt->fetch(PDO::FETCH_ASSOC);
-            $invoiceId = "CB" . date('my') . ($lastInvoice ? ($lastInvoice['id'] + 1) : '1');
+
+            $nextId = $lastInvoice ? ($lastInvoice['id'] + 1) : 1;
+
+            // Ensure the ID is always three digits (e.g., 001, 010, 100)
+            $invoiceId = "CB" . date('my') . str_pad($nextId, 3, '0', STR_PAD_LEFT);
 
             $stmt = $db->query("SELECT invoiceId FROM invoice ORDER BY id DESC LIMIT 1");
             $lastInvoicePrint = $stmt->fetch(PDO::FETCH_ASSOC);