Illinois property tax is paid in arrears. I paid for 2015 taxes in 2016, then sold my house in Nov 2016 and paid 11/12ths of 2016 taxes to buyer. Is this all deductible

[Howard1948]

As xmababy0 said above, the answer is Yes as it relates to itemized deductions on Schedule A of your Federal income tax return.

That being said, be careful in IL when preparing your calculation of the IL property tax credit of 5% of your qualified property tax payments.  That calculation is not based on "no matter what year they were for" but is based only on 2015 taxes paid in 2016.  Since your 11/12ths payment is for 2016 taxes and not for 2015 taxes, they should not be included in this credit calculation for this year's return.

[xmasbaby0]

Whatever you paid in property taxes in 2016 can be entered on your 2016 tax return--no matter what year they were "for."