How do Invoice and record a payment for clients who have already paid?

Hey there, @thesocialpreneur.

You can simply record the invoice and its payment as usual inside QuickBooks Online (QBO). This way, you can keep your books accurate once you reconcile your account.

Here's how create an invoice and record its payment:

1. Click the +New icon and select Invoice.
2. Choose the customer in the Customer drop-down and fill out the rest of the information.
3. Select Save and close. 
4. After this, click again the +New icon and select Receive payment.
5. In the Customer drop-down list, choose the customer and fill out the rest of the information.
6. Check the box for the invoice that you wanted to categorize as paid.
7. Click Save and close.

Additionally, you can run the Invoices and Receive Payments report in QuickBooks Online (QBO). This will show you the list of payments that you've received and the invoices that go with them. Go to Reports and look for the Invoices and Receive Payments report.
 

Don't hesitate to tag my name in the comment section below if you have other concerns or questions. I'm always ready to help. Have a great weekend.