Hi there, @tallenDPI.

At this time, there isn't an option to automatically calculate early pay discounts on vendor bills in QuickBooks Online (QBO). As mentioned by my peer above, you can consider creating a vendor credit as a discount and apply it when paying your bills as an alternative.

I can see how useful it is for you and your business to have this option. But I want to let you know that your voice matters and I'm submitting feedback directly to our product engineers for consideration.

For now, you can visit our blog site so you'll be able to get the latest news about QuickBooks and what our Product Care Team is working on. 

If you have other concerns, just comment below or post again. I'll be sure to get back to you. Have a good one.