The Tax Cuts and Jobs Act (TCJA), passed on December 22, 2017, marks a significant change in federal tax law affecting small businesses starting with the 2018 tax year. Key changes include a 20% deduction for pass-through entities, a flat corporate tax rate of 21%, increased IRC §179 expenses, and limitations on certain deductions such as entertainment expenses. Businesses must consider these changes for their tax strategies and consult with advisors to understand the implications on their specific situations.