Prisoner Incentive Act of 2015

Amends the federal criminal code to: (1) allow federal prisoners to earn up to 54 days of credit toward the service of a sentence for each year of the prisoner's sentence imposed by the court if the Bureau of Prisons determines the prisoner has displayed exemplary compliance with institutional disciplinary regulations; and (2) authorize the Bureau to restore credit previously denied to a prisoner, based on such prisoner maintaining good behavior. Makes this Act applicable to each prison sentence that has not been completed before the date of enactment, except any sentence imposed before November 1, 1987.