If the feds charge X% and the state charges Y%, then it is entirely possible that x + Y > 100%. When SALT is deductible, it prevents that scenario. That isn't

If the feds charge X% and the state charges Y%, then it is entirely possible that x + Y > 100%. When SALT is deductible, it prevents that scenario. That isn't the case today, but it is well within the realm of possibility if, say, one the Democrats' maximum-tax-rate proposals are enacted (which I broadly support). The states and the feds historically don't coordinate taxes well, but the SALT deduction was one way of coordinating. It hasn't been replaced by anything, and it needs to be.