This feature is applicable for the customers/invoices for which payment terms are defined at customer record/invoice level. This functionality provides the users to give discount to the customers who pay upfront than the payment terms.
Payment terms are defined in accounting lists. At setup level it was defined the discount as 10% if company pays the bill to vendor within 30 days of the bill date.
If an invoice is raised with payment terms as NET 30
Discount avail at customer payment screen
If customer makes the payment within the 30 days from the bill date, NetSuite automatically shows the discount that the customer can get in discount avail field. User can decide upon the amount that can be given by entering the discount in discount taken field. The discount entered in this screen will be posted to the discount account setup in the accounting preferences.