diff --git a/application/language/en-GB/sales_lang.php b/application/language/en-GB/sales_lang.php
index 961a29a71..c3caa9a47 100644
--- a/application/language/en-GB/sales_lang.php
+++ b/application/language/en-GB/sales_lang.php
@@ -174,3 +174,4 @@ $lang["sales_work_order_number"] = "Work Order Number";
 $lang["sales_work_order_number_duplicate"] = "Work Order Number must be unique";
 $lang["sales_work_order_sent"] = "Work Order sent to";
 $lang["sales_work_order_unsent"] = "Work Order failed to be sent to";
+$lang["sales_customer_optional"] = "(Required for Due Payments)";
\ No newline at end of file