diff --git a/Front-End/src/components/PaymentPlanSelector.js b/Front-End/src/components/PaymentPlanSelector.js
index f94fc50..e3b0c40 100644
--- a/Front-End/src/components/PaymentPlanSelector.js
+++ b/Front-End/src/components/PaymentPlanSelector.js
@@ -124,25 +124,40 @@ const PaymentPlanSelector = ({
 
   const handleRowClick = (row) => {
     const value = row.id;
+
     if (selectedFrequency === value) {
       setSelectedFrequency(null); // Désélectionner l'onglet si la ligne est déjà sélectionnée
     } else {
       setSelectedFrequency(value);
+
       if (!dates[value]) {
         const frequencyValue =
           paymentPlansOptions.find((plan) => plan.id === value)?.frequency || 1;
+
         const newDates = Array(frequencyValue)
           .fill('')
           .map((_, index) => {
             const newDate = new Date();
-            newDate.setDate(defaultDay);
+
+            // Validate defaultDay
+            const day =
+              typeof defaultDay === 'number' &&
+              defaultDay >= 1 &&
+              defaultDay <= 31
+                ? defaultDay
+                : 1; // Fallback to 1 if defaultDay is invalid
+
+            newDate.setDate(day);
+
             if (value === 1) {
               newDate.setMonth(newDate.getMonth() + index * 4); // Espacer de 4 mois pour le paiement en 3 fois
             } else {
               newDate.setMonth(newDate.getMonth() + index);
             }
+
             return newDate.toISOString().split('T')[0];
           });
+
         setDates((prevDates) => ({ ...prevDates, [value]: newDates }));
       }
     }