President Trump touts his plan to cut the corporate tax rate as one of the biggest tax cuts ever, as if he’s the first to propose such a thing. Practically forgotten is the fact that Trump’s predecessor, President Obama, also pushed for a cut in the corporate tax rate, which indicates rare bipartisan agreement, at least on the principle of reforming the corporate tax code.

Trump wants to slash the top corporate rate from 35% to 15%. Obama favored a more modest reduction, to 28%. While there’s a big gap between those two targets, Trump’s 15% rate is widely viewed as an opening bid that’s not plausible in reality. Congress could ultimately approve a rate between 20% and 25%, close to Obama’s target. Had the Republican-controlled Congress been willing to pursue Obama’s plan in 2015 or 2016—which it wasn’t—the final outcome could have been nearly the same as whatever happens with Trump’s plan.

Ordinary folks might wonder why it’s so important to cut taxes for corporations when profits are strong and the stock market is going gangbusters. If other countries had a top corporate rate comparable to the one in the United States, there’d be no reason for a reduction. But other developed countries have been cutting corporate taxes, as competition to lure big global employers has intensified. That has left the US with one of the highest corporate rates in the developed world.

Here are a few of the top rates around the world, including average state and local taxes on corporations:

United States: 38.91%

France: 34.43%

Germany: 30.18%

Australia: 30%

Japan: 29.97%

Canada: 26.7%

United Kingdom: 19%

Ireland: 12.5%

Of 35 countries tracked by the Organization for Economic Cooperation and Development, the United States has the highest top rate. Many companies use credits and deductions to sharply lower the taxes they pay, but even that causes problems because some companies, such as real-estate developers, get generous breaks, while others, like healthcare companies, get relatively few. US tax law also favors companies with major foreign operations over those that mostly operate domestically and have far less access to overseas tax shelters.

The big disparity between rates in the United States and in other countries is one factor encouraging “corporate inversions” in which companies based in the United States make deals with foreign companies and relocate their headquarters to those countries, in order to take advantage of lower rates. It also explains much of the $2 trillion in profits that big companies such as Apple (AAPL), Microsoft (MSFT), Alphabet (GOOGL), General Electric (GE) and Pfizer (PFE) have stashed in foreign countries such as Ireland and Luxembourg, instead of bringing it back to the US and spending or investing it here.