State income taxes paid in 2021 cannot be deducted on the 2020 tax return. They can be deducted on the 2021 federal tax return that is filed next year.
The sales tax deduction can be used on the 2020 federal tax return and on the 2021 tax return.
The state income tax deduction and the sales tax deduction is not an either one or the other, both can be deducted on the same tax return.
