Strong Families Act This bill amends the Internal Revenue Code to: (1) allow certain employers a business-related tax credit for a specified percentage (not to exceed 25%) of the amount of wages paid to their employees during any period (not exceeding 12 weeks) in which such employees are on family and medical leave, (2) limit the allowable amount of such credit with respect to any employee to the product of the normal hourly wage rate of such employee for each hour (or fraction thereof) of actual services performed for the employer and the number of hours (or fraction thereof) for which family and medical leave is taken, and (3) terminate such credit five years after the enactment of this bill. The Government Accountability Office shall complete a study on the effectiveness of the tax credit for paid family and medical leave.