Strong Families Act This bill amends the Internal Revenue Code to: (1) allow certain employers a business-related tax credit for up to 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 to $3,000 per employee for any taxable year, and (3) terminate such credit two 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. The Office of Management and Budget shall determine: (1) the dollar amount obligated by each executive agency to purchase and to lease civilian vehicles in FY2010, and (2) the total number of civilian vehicles purchased and leased by each executive agency in FY2010. Executive agencies may not obligate more than 90% of the amount they obligated in FY2010 to purchase or lease civilian vehicles in each of FY2017-FY2021. The bill permanently rescinds all unobligated amounts in the U.S. Enrichment Corporation Fund, except for amounts designated as an emergency requirement.