You cannot. You can only deduct property tax in the tax year that it was paid.
Many people pay there property tax for the year and also prepay the next years tax so as to double the deduction for one year and not deduct anything the next year.
And at the moment there's no way to know how the final taxcut bill (if one is passed) will affect itemized deductions next year. Depending on what deductions are removed, people who normally itemize deductions may no longer be able to, although they may get a larger standard deduction. And the larger standard deduction will make the hurdle higher for some people who are currently used to itemizing.
And property taxes might not be a deduction at all in 2018.
Yes, the new tax bill is an unknown for now. So, I have to make the assumption that property tax deductions will remain. Which leave me with the same question.
A bit more detail seems needed. Taxes are due in 2017. If I dely there is a pretty stiff penalty. So, I want to pay the tax before the end of 2017 to avoid the penalty. BUT, I am unable to take the payment as a deduction this year. Next year I will have a taxable situation that will allow me to take the deduction. So, I am trying to pay now, to avoid the penalty, but take the deduction for 2018 taxes to avoid taxes. (without regard to the potential that the entire tax process will blow up next year)
A bit more detail seems needed. Taxes are due in 2017. If I dely there is a pretty stiff penalty. So, I want to pay the tax before the end of 2017 to avoid the penalty. BUT, I am unable to take the payment as a deduction this year. Next year I will have a taxable situation that will allow me to take the deduction. So, I am trying to pay now, to avoid the penalty, but take the deduction for 2018 taxes to avoid taxes. (without regard to the potential that the entire tax process will blow up next year)
Read my answer above. Anything *paid* in 2017 can only be reported on 2017 taxes. If you pay in 2017 you either deduct it in 2017 or not at all.
You can't save up deductions for a future year when you can use the itemized instead of the standard deduction. The only way to claim the tax deduction in 2018 is to actually pay the tax bill on or after January 1, 2018. If that means you have to eat a late payment penalty from the city or county, you will have to decide whether it is worth it.
Note that if you try and do something clever like paying in December with a post-dated check, and the city successfully deposits the check in 2017, then it's a 2017 payment even though the check is dated 2018.
Be sure and check the deadline on your statement. In some locations (like mine), 2017 property taxes may have a January 2018 deadline, which provides for more flexibility. I plan to wait until late in December to decide when to pay.
And the idea of a post-dated check will not work. Post-dated checks only work if the check is given to a trusted individual that has agreed to not deposit it until the date on the check.
Once a check is signed it becomes negotiable reguardless of the date. Government agencies are not going to look at the date, they will simply deposit the check along with the thousands of other checks as soon as it is received. Their banks computer that reads the deposited checks will pay no attention to the date which is really for your information.