Many large and successful businesses pay surprisingly little corporate income tax — including the infamous case of Amazon paying $0 in tax last year.

The sense that corporations aren’t paying their fair share of the nation’s tax burden is a perennial complaint in public opinion polling and today Elizabeth Warren is rolling out a new proposal to do something about it — she calls it the “real corporate profits tax” though tax nerds might see it as akin to the Alternative Minimum Tax that’s levied on some individuals.

In particular, Warren wants to target the fact that many corporations with little to no taxable income nonetheless report significant profits on the earnings statements they send to investors. They have one set of books they show the IRS and another that they show to Wall Street. That’s not accounting fraud or anything, it’s simply that the corporate tax code is complicated and companies avail themselves of any number of loopholes, deductions, and other creative tactics to minimize their tax bills.

Warren’s plan is have the tax code treat those reported profits seriously — and levy a 7 percent tax on them.

How Warren’s real corporate tax plan works

Right now, businesses tally up their taxable income and then pay corporate income tax at a 21 percent rate.

Warren wants to leave that system in place for any company’s first $100 million in profits reported to investors. But for companies with over $100 million in profits (that’s about 1200 companies) a second system kicks in. For every dollar of profit over $100 million that you report, you need to pay a 7 percent tax.

Last year, Amazon reported over $1o billion in profits to investors but paid $0 in corporate income tax. Under Warren’s plan, they would pay about $698 million in taxes instead. Her team has released an analysis from the economists Gabriel Zucman and Emannuel Saez which says this would bring in about $1.04 trillion over a 10-year time span — essentially undoing the $1 trillion in business tax cuts that Trump signed into law, but with the impact concentrated on a smallish number of very profitable companies.

Will this crush investment?

The case against any kind of increased revenue from taxing corporate profits is that these taxes discourage business investment.

People invest in order to reap profits so when you tax profits you are, in effect, taxing investment. And in the long-run, business investment should theoretically lead to more hiring, more productivity, and higher wages. Indeed, one reason the existing corporate tax code is so convoluted is that it has a lot of provisions that are designed to encourage investment and offset any potential negative impact.

Imposing a new flat tax with no deductions and no distortions — even at a relatively low rate — would undo those efforts.

Now of course there are questions about whether this theoretical link between taxes and investment really holds. Empirical research has tended to cast some doubt on it, and the overall conditions in the economy have changed a lot from the 1970s. We’re now in an era where it is fairly cheap and easy for companies to raise funds for investment when they want to, and CEOs did not respond to Trump’s tax cuts by raising investment levels.

Taxing big business, meanwhile, is very popular with the public even though wiping out loopholes and deductions is incredibly unpopular among K Street lobbyists.