By influencing incentives, taxes can affect both supply and demand factors. Reducing marginal tax rates on wages and salaries, for example, can induce people to work more. Expanding the earned income tax credit can bring more low-skilled workers into the labor force. Lower marginal tax rates on the returns to assets (such as interest, dividends, and capital gains) can encourage saving. Reducing marginal tax rates on business income can cause some companies to invest domestically rather than abroad. Tax breaks for research can encourage the creation of new ideas that spill over to help the broader economy. And so on.

Note, however, that tax reductions can also have negative supply effects. If a cut increases workers’ after-tax income, some may choose to work less and take more leisure. This “income effect” pushes against the “substitution effect,” in which lower tax rates at the margin increase the financial reward of working.

Tax provisions can also distort how investment capital is deployed. Our current tax system, for example, favors housing over other types of investment. That differential likely induces overinvestment in housing and reduces economic output and social welfare.