This brief but important letter notifies a customer that he or she has overpaid you. It can serve as a very good customer relations letter.For the open invoice in the Payment column, enter how much of the credit you want to apply. Use the free New Jersey Online Filing Service to file your 2024 NJ-1040 return. It's simple and easy to follow the instructions, complete your NJ tax return,. The only way to fix this is to either refund the excess payment to a gift card or allow the customer to purchase a gift card for a later use. You must be able to prove you lived in the county when the now-defunct tax was collected.