When negative price concessions are enabled, users have the ability to input a negative value for the concession amount as either a dollar or percentage amount. Negative price concessions can be used to offset a previously accepted price concession.
When enabled, users will be able to submit a negative dollar or percentage value on a price concession request at initial lock: 
Or with a Price Concession Change Request:
Negative price concessions must be enabled on the Price Concession Policy by selecting the “Allow negative price concessions” checkbox. Refer to the Configuring Price Concession Change Requests user guide for additional information.
