This paper examines the Tax Cuts and Jobs Act (TCJA) of 2017, the largest tax overhaul since 1986. The new tax law makes substantial changes to the rates and bases of both the individual and corporate income taxes, cutting the corporate income tax rate to 21 percent, redesigning international tax rules, and providing a deduction for pass-through income. TCJA will stimulate the economy in the near term. Most models indicate that the long-term impact on GDP will be small. The impact will be smaller on GNP than on GDP because the law will generate net capital inflows from abroad that have to be repaid in the future. The new law will reduce federal revenues by significant amounts, even after allowing for the modest impact on economic growth. It will make the distribution of after-tax income more unequal, raise federal debt, and impose burdens on future generations. When it is ultimately financed with spending cuts or other tax increases, as it must be in the long run, TCJA will, under the most plausible scenarios, end up making most households worse off than if TCJA had not been enacted. The new law simplifies taxes in some ways but creates new complexity and compliance issues in others. It will raise health care premiums and reduce health insurance coverage and will have adverse effects on charitable contributions and some state and local governments. Looking forward, the ultimate effects of TCJA will depend on the currently uncertain responses of other countries, the Federal Reserve Board, and future Congresses, among others.