“In their 2017 tax bill, Republicans partially closed a tax loophole that mainly affected higher-income people in high-tax areas — i.e., relatively well-off people in blue states. They capped the state and local tax deduction (SALT) people can take when calculating their federal income tax at $10,000. People can still deduct state and local taxes from their federal tax bill, but only up to that point.
Many Democrats — namely, those from states such as New York, New Jersey, and California — want to repeal the SALT deduction cap and go back to the old regime, where people could deduct all (or at least more) of their state and local taxes. They argue the cap unfairly drives up their constituents’ tax bills, might keep their states from implementing more progressive tax regimes on high-income people, and was a vindictive move by the GOP in the first place.”
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“But some Democrats, Republicans, and economists are saying hold the phone.
“The vast majority of the benefits of repealing the SALT cap would go to the people at the very top. It would also be costly — and for that amount, we could finance much more worthy efforts to support American families and workers. We can say we are for a progressive tax code and for fighting inequality, or we can support the SALT deduction, but it is really hard to do both,” said Sen. Michael Bennet (D-CO) in a statement to Vox. When the Senate took up a vote on whether to repeal the SALT cap in December 2019, he was the only Democrat to vote against it.”
https://www.vox.com/policy-and-politics/2021/4/14/22375306/salt-tax-deduction-repeal