Excluding items from discount on invoice created by API

Hello @ilan_workiz, I'm here to guide you through creating a discount.

Normally, when creating an invoice with discounts in QuickBooks Online, this is what we're going to do: 

• To begin with, let's create a service item for the discount: 

1.  Navigate to Sales, then go to Products and Services. 
2. Click New, then select Service.
3. Name it Discount.
4. From the Income Account, choose Discount Given.
5. Scroll down to Sales Tax, then click Edit Sales Tax.
6. Make it Non-taxable, then click Done. 
7. Save and Close.

• After this, let's create the invoice: 

1. Click the +New, then choose Invoice.
2. Add items A and B, then add the service item we made. 
3. Enter the Discount amount (ex.-20)
4. Click Add Subtotal, then add item C.
5. Save and Close.

Here's a screenshot for your visual reference: 

However, since you're using an API, I recommend contacting our Intuit Developers for better advice:

1. Go to this link: Intuit Developer Support.
2. Log in to your Intuit Developer Account or Create a new one.
3. Below the What you need help with, choose QuickBooks Online.
4. Click Ask a question.
5. Hit Ask.
    

Also, I've added this article to help you personalize your invoices: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Let me know if you need further assistance managing your invoice or QuickBooks. Keep safe.