As a presidential candidate, Joe Biden promised not to raise taxes on households earning less than $400,000. Biden has not raised any taxes that would directly hit Americans under that income level. But there's an asterisk: He enacted some changes in corporate taxation.

Corporate tax increases tend to focus most heavily on wealthy individuals. Still, it's possible for some lower-income earners to feel a corporate tax increase's effects. 

For instance, a higher corporate tax could depress the values of shares owned by middle- and lower-income taxpayers, or companies could decide against making investments that increase productivity, which over the long term could reduce workers' wages.

But tax experts say the effect is modest, and the impact can only be loosely modeled rather than observed and tracked directly. 

The Urban Institute-Brookings Institution Tax Policy Center modeled the tax changes from the Inflation Reduction Act of 2022, the major bill Biden signed that included corporate tax provisions. It found that the bottom 80% of earners, which covers households earning up to about $183,000, would see a reduction in taxes owed. 

Households earning between $183,000 and $281,000 saw an increase in taxes of $70, or less than 0.1% of income earned. Households earning between $281,000 and $409,000 saw an increase of $170, also less than 0.1% of income earned.

"President Biden did focus his tax hikes on corporations and higher earners," said Garrett Watson, a senior policy analyst for the Tax Foundation, a think tank. Although corporate tax burdens do hit Americans of more typical incomes, the mechanism is so indirect that it's probably "not in scope" for measuring whether Biden stuck to his promise.

The pass-along effect of corporate taxes is real, including for households earning less than $400,000. However, to the extent the impact can be measured, it tends to be small, and the vast majority of what Biden did on tax policy adhered to his campaign pledge. 

On balance, we rate this a Promise Kept.

Joe Biden's campaign promise not to raise taxes on households earning less than $400,000 a year may seem straightforward. But in the byzantine world of tax policy, it's anything but.

So far, Biden has not proposed raising any taxes that would directly hit Americans under that income level. However, he has proposed a hike in the corporate income tax, and that change could conceivably affect some Americans earning less than $400,000 annually.

Specifically, Biden has said that his American Jobs Plan — a proposal to spend some $2.65 trillion on both traditional and non-traditional forms of infrastructure — would be paid for by raising the corporate income tax from 21% to 28%. (Sen. Joe Manchin, D-W.Va., whose vote would be necessary to pass the plan into law, has said he wouldn't vote for an increase higher than 25%.)

"Generally speaking, a corporate tax increase is highly progressive — it falls most heavily on wealthy individuals," said Thornton Matheson, a senior fellow at the Urban Institute-Brookings Institution Tax Policy Center. 

That said, it's possible some lower earners would feel the effects of a corporate tax increase. For instance, a higher corporate tax could depress the values for shares that middle- and lower-income taxpayers own, or companies could decide against making investments that increase productivity, which over the long term could reduce workers' wages.

But the effect would likely be small, and when analyzing Biden's promise, there's a relevant distinction between a direct tax and an indirect effect of a tax. 

Meanwhile, several tax analysts told PolitiFact that while Biden's promise may have been politically shrewd, it may not be such wise policy.

"Trying to avoid every instance of a tax increase on those making less than $400,000 will make the tax code more complex than it needs to be," said Kyle Pomerleau, a resident fellow at the American Enterprise Institute. "It will also take certain policies off the table entirely. For example, a gas tax or carbon tax would be reasonable ways to raise revenue for infrastructure."

The fact that he has so far refrained from proposing direct tax hikes on Americans earning $400,000 a year or less is enough to rate the promise In the Works.