Greetings, @Blue-River.
Thanks for joining this conversation. Allow me to chime in for a moment and share some information about creating a credit for a customer in QuickBooks.
Just to confirm, are you using the QuickBooks Desktop (QBDT) version? If so, the steps below will show you how to credit a sales tax that was charged to your customer.
To start off, you need to create a credit memo:
1. Go to Customers menu at the top, then pick Create Credit Memos/Refunds on the drop-down.
2. Enter the necessary information. Make sure that it'll match to the original invoice items and quantity (including the sales tax amount).
3. Enter the current date, then Save & Close.
Next is to create a new invoice, here's how:
1. Go back to Customers menu, then pick Create Invoices on the drop-down.
2. Enter the necessary information. This should match the original invoice for the same items but mark them Non-Taxable using today's date.
Once done, go to Receive Payments page, then apply the credit to the invoice. For your reference, you can also check out this article for further guidance: Refund sales tax collected from tax-exempt customers.
That's it! Please let me know how it goes or if you're referring to something else in the comment section below. I'm only a post away should you have any additional questions or concerns. Take care and have a great rest of the day!