Last year 55 Fortune 500 companies paid no U.S. income tax. How can they get away with that?

It seems an outrage when, in any given year, dozens of profitable U.S. corporations pay no U.S. income tax. And maybe it is an outrage—you decide—but realize first that, as usual with tax matters, the reality isn’t as simple as headlines suggest.

Last year at least 55 major, profitable U.S. corporations paid no U.S. income tax, reports the Institute on Taxation and Economic Policy. Some are famous —Nike, FedEx, Salesforce.com—and all are in the Fortune 500 or the S&P 500. How can they get away with that?

The first thing to understand is that the statement “profitable U.S. corporations paid no U.S. income tax” can be misleading. Every big publicly traded company is required to keep two sets of books. The financial statements a company files with the Securities and Exchange Commission (SEC) use Generally Accepted Accounting Principles (GAAP). But when the company files its taxes, it’s required to use a completely different set of accounting rules for the IRS. So in any given year, a company can be profitable according to SEC accounting rules but not profitable according to IRS accounting rules—in which case it would pay no income tax.

The differences between those two sets of rules can be significant. For example, the Tax Cuts and Jobs Act of 2017 (TCJA) lets companies “expense” major investments for tax purposes—deducting the investment’s total cost from taxable income in the year it was made rather than spreading the deduction over many years, as is normally required. If a company spent $1 billion on a new factory last year, it probably deducted that whole amount from its taxable income—but only on its 2020 tax return. In its SEC filings, using GAAP rules, it still had to spread that deduction over many years, perhaps $50 million a year over the factory’s 20-year expected life. A few investments like that could result in an SEC-profitable company that’s also an IRS-unprofitable company, which therefore owes no tax.

The tax code includes many rules that result in much lower profits reported on a company’s tax return than in its SEC filings. Expenses of employee stock options can be much larger under IRS rules than under SEC rules. Last year’s CARES Act allowed companies to “carry back” losses from 2018 or 2019 and apply them against profits from earlier years. Some companies thus got rebates from the IRS; in some cases the amount exceeded taxes otherwise owed, so companies got a check from the IRS.

Companies also reduce U.S. tax by shifting profits out of the U.S. to low-tax or no-tax countries, though under the TCJA, companies must pay at least some tax on non-U.S. profits. It’s not clear whether profit-shifting was a significant tax reducer for the 55 no-U.S.-tax companies of 2020. The largest category of companies on the list is gas and electric utilities, which are overwhelmingly domestic operations.

Even if a company has taxable income under IRS rules, it can still avoid tax by using tax credits, which are applied directly against tax to reduce or eliminate the amount owed. That may be a reason so many utilities are on the list; they receive substantial renewable energy tax credits. They also invest billions in infrastructure, so they benefited from the TCJA rule that allows expensing of investments. That rule begins to phase out in 2023 and expires at the end of 2026.

The big picture is that major corporations can avoid tax legally using tax breaks enacted by Congress. Those tax breaks are bipartisan. While the TCJA was passed with no Democratic votes, renewable energy tax credits attract strong Democratic support. The CARES Act was passed unanimously in the Senate and nearly so in the House. The research and development tax credit, another important corporate tax break, was made permanent in 2015 with bipartisan majorities in both houses.

So is it outrageous when big U.S. corporations pay no U.S. income tax? Possibly not, in cases where tax breaks incentivized companies toward worthy behavior. And if it is outrageous, who’s to blame, companies or Congress? That’s a large and important question, and because it involves tax policy, it’s never going to be simple.