Thanks for coming back, Antarse2600.

Currently, this feature isn't available in all country versions. Rest assured, I'll send feedback to our engineers about this. They can consider this option be added in the future update.

Meanwhile, you can add a new line item for your discount in your invoice and enter the amount as negative. Let me show you how.

1. Click +New.
2. Click Invoice. Then, enter invoice details.
3. Click the line after your product/service item. Then, click the drop-down and click Add new.
4. Select Service and enter "Discount" as your Name.
5. Select the account. Then, click Save and close.
6. Back in the invoice page, enter a negative amount for your discount.
7. Click Save and close.

The screenshot will show how it looks like to add the discount as a line item.

You can also check this page for more help articles about managing customers and income.

Get back to me if you have other concerns. I'll be around for you.