Good day, QuickWin.

I'll help you set up the rebate in QuickBooks Online.

You can create a service item that will represent the rebate. Then, edit the invoice or sales receipt and it to the second line whenever the customer is entitled to receive it. Here's how: 

1. Go to the Gear icon and select Products and Services.
2. Click New in the upper-right hand corner, then select Service.
3. Enter the name of the rebate and select an Income account.
4. Provide all other details of the item.
5. Click Save and close.

Once done, open the invoice or sales receipt and add it to the second line of the transaction. 

You can also follow these steps to run a report for this item:

1. Go to back to the Products and Services section and look for the rebate.
2. Click the drop-down list beside Edit.
3. Select Run report.

Just in case the client chooses to upgrade the QBO subscription, you can keep this article for future reference: Add a Discount to an Invoice or Sales Receipt in QuickBooks Online.

Please don't hesitate to reach out to us again if you have other questions. I'd be glad to jump right back to help you again.