When I create Invoice via API, I add discount to that Invoice, but Invoice is creating withount any discount. I tried with percent and amount - everytime discount EMPTY

Hello roman, 

There are several possible reasons for this issue. In this case, there might be a bug in the API itself that's preventing the discount from being applied correctly.  I'd suggest double-checking the API request you're sending to make sure the discount info is getting included properly.

Still, I suggest contacting Intuit's developer support team to figure out why the discount isn't showing up on your API-created invoices every time. They are equipped to assist with API-related problems and can provide guidance on how to properly add discounts to your invoices via the API.

1. Visit Intuit Developer. 
2. Click Help.
3. To continue the process, you'll need to either Sign in if you already have an existing account or Create Account to create one.

Additionally, here are some articles that provide step-by-step instructions on how to personalize your sales forms and record incoming invoices:

• Customize invoices, estimates, and sales receipts
• Receive and record invoices.

If you have further questions about managing invoice and invoice payments in QuickBooks, please post again. I'm here to assist you.