Hi

Thanks for using Sage City

If there is an underpayment then allocate the payment against an invoice which will leave an outstanding value on the invoice, then raise a credit note for the remaining value to show the invoice as fully paid.

If this needs to be written off as a bad debt then follow this article: https://help.accounting.sage.com/en-gb/accounting/cashflow/extra-bad-debt.html

If it is an overpayment, then again, allocate the payment to the invoice to clear the invoice and leave the extra value as a payment on account. This can then be allocated to future invoices, or refunded if appropriate

If you need any further assistance please call Sage Business Cloud Support on 0191 479 5911 (this line is open 24/7)

Regards