CHE reports (drawing on various sources, which have slightly different details):

[T]he proposed new system would be tiered, and only colleges with endowments valued at more than $750,000 per student would pay a higher tax rate. (Currently, colleges that have endowments valued at $500,000 or more per student — and meet certain other conditions — pay a 1.4-percent tax on endowment earnings. Fifty-six institutions paid the tax in 2023, according to the Internal Revenue Service.)

In one version of the newly proposed structure, reported by Punchbowl News, colleges with endowment values over $2 million per student — fewer than half a dozen — would pay a 21-percent tax rate on endowment earnings. Princeton and Yale Universities and the Massachusetts Institute for Technology could qualify for this bracket, according to an analysis by James Murphy, who leads Education Reform Now. Depending on how you calculate value, Stanford and Harvard Universities could fall into either this group or the one just below it.

The next group in the breakdown reported by Punchbowl News — subject to a 14-percent tax rate on earnings — covers endowment values between $1.25 million and $2 million per student, which could include a group of roughly 10 institutions like Amherst, Swarthmore, and Grinnell Colleges, and the California Institute of Technology.

Then there’s a third group in that proposal, covering endowment values between $750,000 and $1.25 million per student that would pay a 7-percent rate. That could include roughly a dozen institutions, such as Wellesley and Claremont McKenna Colleges and Washington and Lee University, and potentially the University of Pennsylvania — again, depending on how you calculate value.

In the tiered structure reported by Politico, the tax rates would be 10 percent for colleges with endowment values between $750,000 and $1 million per student, and 20 percent for colleges with values over $1 million.

Major research universities with lower per-student endowments–like UChicago, Columbia, Cornell and Johns Hopkins–will be spared, although UChicago, at least, will continue to pay the 1.4% rate.  Northwestern, based on endowment numbers from a couple of years ago, may be on the cusp of a higher rate.  (The Murphy list, cited by CHE above, does not include UChicago, even though we pay the endowment tax, which leads me to wonder about how he is calculating the figures.)