I’m sorry to hear about the contract, @kstark680.
You can close out the open invoice with the amount left by your customer. Create a credit memo in QuickBooks first to record the transaction.
Now the credit sits on the account and is waiting for you to attach it to an invoice. Follow the steps below to apply the transaction:
See Enter and apply a credit memo on this article for more information: Credit memo or delayed credit.
Let me know what else I can do to help. I’m always here if you need more assistance. Have a good one!