Hi there, Chetak Dwarakanath.

Since the books are closed as of February 2020, I suggest creating a journal entry. I also recommend consulting an accountant for guidance in posting the amounts to the correct accounts. They can also help link the JE to an invoice.

Here's how to create journal entry:

1. Click the New icon at the left corner.
2. Choose Journal Entry.
3. Enter the journal date.
4. Fill in the other necessary fields.
5. Hit the Save and Close button.

Please check this article to see steps on how to apply a journal entry as a credit to your customer's open invoice: How to apply a journal entry credit to an invoice.

You can also refer to this article on how you can receive and categorize invoice payments: Record invoice payments in QuickBooks Online. This also provides information on how to group multiple payments together into a single record.

Please know that you're always welcome to post if you have any other concerns. Wishing you and your business continued success.