As a candidate, President Joe Biden proposed raising the federal tax rate on corporations from 21% to 28%, so that "wealthy Americans and big corporations pay their fair share."

But after pushback in Congress, Biden pursued a different approach. Now that the Senate passed a bill negotiated by Democratic Sens. Joe Manchin of West Virginia and Chuck Schumer of New York on Aug. 7, taxes for some of the nation's largest companies are poised to increase, though not in the across-the-board fashion Biden envisioned.

Under the bill the Senate passed, corporations that have profits exceeding $1 billion for three consecutive years would face a new minimum 15% tax on corporate "book income," which generally means the amount companies report to investors. 

The provision, which would be effective for tax years beginning after Dec. 31, 2022, seeks to ensure that if companies are reporting large profits to investors, they can't simultaneously game the system by reporting smaller profits for tax purposes.

Having two different sets of rules "helps explain why some large profitable companies pay very little in federal corporate income taxes," the Urban Institute-Brookings Institution Tax Policy Center has written.

Passing the Senate was the bill's largest hurdle; the measure now moves to the House, where it is expected to pass. From there, it goes to the White House, where Biden has pledged to sign it.

The Tax Foundation, a nonpartisan Washington, D.C.-based think tank, projects the provision would raise $200 billion over 10 years but added that the figure would be lower if big corporations pursue tax avoidance.

Also, the impact would not be uniform. Tax Policy Center analyses suggest the different approaches to taxing corporations could help some sectors and hurt others. For instance, the tax code favors research and capital investments, so using a book rate tax could remove some deductions and credits, hurting capital-intensive sectors such as utilities, transportation and manufacturing.

In any case, there are significant differences in scope and method between what passed and what Biden had promised during the campaign.

"The minimum tax is a parallel tax that firms may, or may not, be subject to in a given year," said Kyle Pomerleau, a senior fellow with the American Enterprise Institute, a center-right think tank also based in Washington, D.C.

We rate the promise a Compromise.