If you have a customer payment that was entered incorrectly, reverse it by entering a negative customer payment. When a negative payment is entered, it will increase the amount the customer owes you and reduce the total on the payments report.
To reverse a customer payment:
Choose Customers, Transactions, Payments, Enter Payments
Enter the same Payment Date as on the original payment
For Payment Amount, enter the original payment amount as a negative value
Choose Accept F9 to allocate the payment
Choose Zero No F12 to view all paid customer invoices
Locate the required invoice number and allocate the negative amount of the original payment to the invoice, then choose Accept F9
