The current U.S. presidential election process not surprisingly features a number of tax reform idea, some well thought out and others not so much. More concrete ideas about overhauling the U.S. tax system are drawing attention, as the recent conversation around former Florida Governor Jeb Bush’s plan shows. The focus is often on the individual tax system, however, with more detailed proposed changes to the corporate tax system often overshadowed.

There are two big areas in the debate about the U.S. corporate tax system: the rate and the coverage. When it comes to the rate, there’s an important distinction to be made. You’ll hear some claim that the United States has the highest corporate income tax among developed economies. That’s statement is strictly true. The statutory corporate income tax, or the rate that’s on the books, 39.1 percent, is the highest among the developed and leading developing economies in the Organisation for Economic Co-operation and Development.

Yet the statutory rate is quite different from the effective tax rate, or the rate corporations actually pay. The difference is due to the variety of deductions and loopholes present in the current system. Estimates of the effective rate differ, but according to the U.S. Congressional Budget Office the effective rate averaged 25.4 percent from 1987 to 2008, or about the current average of 24.8 percent for the other 33 economies in the OECD.

What’s more, there is some evidence that points to a much lower effective tax rate. Research by economist Patrick Driessen at Bloomberg Government points out that models used by the Congressional Budget Office and others calculate the effective tax rate by looking at how the capital gains tax that individuals paid on realized capital gains from investments in corporations. This method ends up missing the significant amount of earnings held by U.S. corporations abroad. Driessen pegs that number at about $400 billion. After accounting for these deferred foreign earnings, Drissen gets a much lower effective rate: about 14 percent,

These foreign earnings bring up the second area of discussion when it comes to the corporate income tax. The U.S. corporate income tax system is currently a worldwide system, where theoretically the profits of a U.S. corporation earned anywhere are taxed at the U.S. rate. But if profits earned elsewhere are kept outside of the United States, then they remain untaxed by the federal and states government. This large stash of profits kept overseas and untaxed is one of the trends highlighted by economist Gabriel Zucman at the London School of Economics in his book, “The Hidden Wealth of Nations.”

Some politicians and economists propose that the United States should deal with these untaxed offshore profits by switching to a “territorial” system, where only profits earned in the United States would be taxed. But there remains the possibility that corporations would figure out how to make profits earned in the United States looks like they were earned elsewhere, as they do now under the current corporate tax system.

Which is all to say that the complexities of the U.S. corporate income tax system are one reason why it often receives less attention than the more-well understood individual tax system, with which citizens have a more visceral relationship. Given the amount of money at stake and the distributional effects of reform, let’s hope the current election cycle sparks a serious debate about the current system.