How to do apply discount an invoice payment?

Good morning, @kimhun.cam.

I'm here to help you apply your discount to your customer.

Although we aren't able to apply a discount to payment in QuickBooks Online, we can apply it to the invoice. Great news, this is a super simple process.

Let's get started:

First, you'll want to turn on the discount feature. To do this:

1. Go to Settings and then choose Account and Settings.
2. Click the Sales tab on the menu.
3. In the Sales form content section, you'll want to hit the pencil icon to edit it.
4. Select the Discount checkbox to turn it on.
5. Then you'll click Save and then Done.

Alright, now that we have that turned on, let's apply the discount. To do this:

1. Click the +New button and choose Invoice.
2. Fill out your invoice as usual.
3. Select the Discount and percentage or Discount value to enter the discount as a percentage or a specific amount.
4. Enter your discount amount. (If you want to discount the total before you calculate sales tax, hit the arrow icon next to the discount field).
5. When you're done, select Save and send or Save and close.

Here's an example of what your invoice will look like with a discount:

That's all there is to it. Please reply to this thread if you have more questions. I'm here to help you get back to business. Take care!