diff --git a/admin/setup_mvp.php b/admin/setup_mvp.php
index 0ad1d19..292631b 100644
--- a/admin/setup_mvp.php
+++ b/admin/setup_mvp.php
@@ -89,6 +89,10 @@ if ($action == 'update_journal_config') {
 
 // Handle VAT refund threshold configuration updates
 if ($action == 'update_vat_refund_threshold') {
+    // Debug: Log all POST data
+    error_log("VAT Refund Threshold Debug - All POST data:");
+    error_log("POST data: " . print_r($_POST, true));
+    
     $threshold_config = array(
         'refund_threshold' => GETPOST('vat_refund_threshold', 'float'),
         'refund_threshold_enabled' => GETPOST('vat_refund_threshold_enabled', 'int')
@@ -628,7 +632,7 @@ print '</div>';
     print '<td><strong>' . $langs->trans("VATRefundThreshold") . '</strong></td>';
     print '<td>';
     print '<small>' . $langs->trans("VATRefundThresholdHelp") . '</small><br>';
-    print '<input type="number" name="vat_refund_threshold" value="' . $threshold_config['refund_threshold'] . '" step="0.01" min="0" class="minwidth200">';
+    print '<input type="number" name="vat_refund_threshold" id="vat_refund_threshold" value="' . $threshold_config['refund_threshold'] . '" step="0.01" min="0" class="minwidth200" required>';
     print '</td>';
     print '</tr>';