Write off an Invoice in QuickBooks is essential for managing uncollectible receivables. To do this, navigate to the “Customers” menu and select “Receive Payments.” Choose the customer and the unpaid invoice. Create a “Credit Memo” from the same menu to offset the invoice amount. Apply the credit memo to the open invoice by selecting “Apply Credit” under the “Receive Payments” window. Ensure the invoice amount is now zero. This process removes the unpaid invoice from your accounts receivable, maintaining accurate financial records and reflecting the loss properly in your books.