Copied from Accounting Today:
"Following enactment of the state and local tax deduction limitation in the Tax Cuts and Jobs Act in 2017, many states began looking for structures to circumvent the limit. These included trying to shift to a deductible charitable contribution, shifting to a payroll tax, and shifting to an entity-level tax.
The Internal Revenue Service took a dim view of the charitable contribution approach, and the payroll tax approach appeared to be too complicated to implement. However, the entity-level tax has been blessed by the IRS, leading to a stampede among states to implement that approach.
Notice 2020-75, issued Nov. 9, 2020, states that the IRS intends to issue proposed regulations clarifying that state and local income taxes imposed on and paid by a partnership or an S corporation are allowed as a deduction by that entity in computing its taxable income or loss in the year of payment. The notice also clarifies that the rule applies in a tax year ending after Dec. 31, 2017, covering the period back to implementation of the state and local tax deduction limit."