In QuickBooks there are a couple of different ways to write off an invoice balance. The simplest way would be to go to the Customer menu and select Receive Payments. Select the name of the customer that you are going to write off the balance for, and the Receive Payments window should show you a list of all outstanding invoices for the customer. Highlight the invoice you want to write off, then click the Discounts and Credits button at the bottom of the screen.
On the Discounts and Credits screen, enter the amount of the write off, and select the account you want to track this too, typically an account called Bad Debt. If you are unsure of the account to use, select Ask My Accountant, and then discuss the best account to use with your accountant.
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