Small Business Tax Fairness and Compliance Simplification Act

S 45 extends a tax credit for employer social security taxes paid on employee tips to beauty service establishments (like salons, spas, and barbershops), directly affecting businesses where tipping is customary for services such as hair care, nail care, or esthetics. It creates a "safe harbor" that protects businesses from IRS tip audits if they implement employee tip reporting training, monthly tip tracking, and maintain records for four years. The bill also requires businesses renting space to beauty service providers (e.g., salon landlords) to report annual rental income over $600 to the IRS. Finally, it mandates a 5-year GAO study on how the tax credit impacts small business tax compliance and employee benefits.