In 2018, I filed for extension for 2 -2017 sate returns and made an extension payment with each. Because we are cash basis, I did not take a deduction on my 2017 federal return for the payments made with the state extensions. When I input the payments as payments in 2018 for 2017 and also report the full refunds from each state, The Form 1040, Line 10, "State and Local Income Tax Refund Worksheet takes my input and treats the payments made in 2018 for 2017 as if they were paid in 2017 and included in the State income tax deducted on Schedule A on my 2017 return. They were not included in 2017 itemized deductions because the payments were made inh 2018.
