I appreciate the clarification that you gave, @QuickWin.

I've got the steps that you need in recording your sales rebate in QuickBooks Online.

You can create a refund for the rebate amount since this was given after the sales receipt was recorded. This way, you can track the discount that you gave.

To do that:

1. Click on + New.
2. Select Refund receipt or Give refund.
3. Click the Customer ▼ dropdown, then select the customer you want to refund.
4. Select the Refund From ▼ dropdown, then select the bank you deposited the payment for the invoice to.
5. Add all products or services the customer returned in the PRODUCT/SERVICE column.
6. Make sure to fill the service date, quantity, rate, amount, tax, and other fields accordingly, then select Save and close.

For more details about handling customer's refund in QBO, please check out this link: Learn how to refund a customer.

To add up, know that QuickBooks Online gives you the option to add discount on your sales transactions. However, this can be done upon creating the sales entry.

Here's how to utilize the feature:

1. Select Settings ⚙ and then Account and Settings.
2. Select the Sales tab on the menu.
3. In the Sales form content section, select the pencil ✏ icon to edit it.
4. Select the Discount checkbox to turn it on.
5. Then select Save and then Done.

This adds the discount field to your invoices and sales receipts. QuickBooks also creates a Discount given account to track everything on your chart of accounts.

To learn more about this process, feel free to scan through this reference: Learn how to discount invoices and sales receipts.

Lastly, here's an article that you can refer about receiving customer's payments in QBO: Learn how to receive and record invoice payments in QuickBooks Online.

Know that you can always get back to me if you need more assistance with managing your sales transactions. Have a lovely day