Hello there, youngerbroslumber.

A vendor discount means you paid less than what was owed.  It should reduce the cost of what was paid for, BUT QB is incapable of doing that.  As a result, the discount amount is, or should be, posted as income to the company.

Vendor discounts help the vendor get his money quicker, but it does add income to your company - your choice. 

I'm adding this article with the topics you can use while recording the common vendor transactions: The Difference Between Bills, Checks, and Expenses in QuickBooks Online.

It'll always be my pleasure to help if you've got additional questions about discounts and payments. Use the Reply option below and surely I'll be here ready to assist you. Take care and stay safe!