Creating a Discount with Other Costs
Step 1. Create an item with a negative selling cost.
Note: There will be no purchase cost, so you can select your firm as a vendor. If you are unable to type in a selling cost without adding it to the purchase cost, select Codes and change Copy Purchase to "Never".
Step 2. Invoice this item along with your other items.

Step 3. Create an Other Cost (Settings | Other Costs) and name it 'DISCOUNT". Choose applicable income and expense accounts.

