diff --git a/src/pages/04_product-service/MainPage.vue b/src/pages/04_product-service/MainPage.vue
index 32ce4028..ea06d88b 100644
--- a/src/pages/04_product-service/MainPage.vue
+++ b/src/pages/04_product-service/MainPage.vue
@@ -952,11 +952,13 @@ async function assignFormDataProductService(id: string) {
     formDataProductService.value.work = prevService.value.work;
 
     workItems.value = res.work.map((item) => {
-      splitPay.value = Math.max(
-        ...item.productOnWork.map(
-          (productOnWorkItem) => productOnWorkItem.installmentNo,
-        ),
+      const maxInstallmentsNo = item.productOnWork.map(
+        (productOnWorkItem) => productOnWorkItem.installmentNo || 0,
       );
+
+      if (splitPay.value < Math.max(...maxInstallmentsNo))
+        splitPay.value = Math.max(...maxInstallmentsNo);
+
       return {
         id: item.id,
         name: item.name,