Explanation of the Discount Items section under the Line Item integration tab.
The fields on this page are mapped to Service items in QuickBooks Online. You’ll need to create the Service item in QuickBooks Online under Sales > Products and Services. Click on the button below to learn about services and how they’re connected to the Chart of Accounts.
Shipping Discount is the discount customers receive on shipping. This can be because of free shipping or Prime orders. This service that you create for this should be mapped to a Type: Income account (Detail Type: Other Primary Income if you’re unsure what to select).
Goodwill Discount is the discount customers are issued by you or customer service representatives.
Promotions is the discount customers receive for any promotional campaigns. If the promotion is sponsored by Amazon, you’ll receive a credit for the discount customers receive.