Hi there, ccdcpreschool. Let me help you how to add a discount for your vendor bill in QuickBooks Online (QBO).
In QBO, adding a discount to your bill is unavailable. What you can do is add a service item on the second line item as a negative amount instead. This way, it won't affect your inventory.
Here's how:
Go to the +New icon, then select Bill.
Click the dropdown button on the Choose a vendor, then choose a vendor.
Enter all the necessary information.
Under the Item details, add an item. Enter the amount.
On the second line item, add a service item. Enter the amount as negative (-20).
Click Save and close once done.
When sending the bill to your vendor, the total amount will show that it's already deducted from the discount. QBO doesn't support sending bills that only display the net payment amount.