Well, that's complicated.
First, property taxes aren't deductible if you pay them before they are actually legally assessed. This created problems last year in New York, among other states, because the legal authority to assess the tax was not conferred on the counties by state law until January 1 (with a due date of Feb 15) so people trying to make payments before January 1 could not legally deduct them because the taxes had not been legally assessed. (I seem to recall the governor issued an executive order to allow counties to assess the tax on Dec 31, giving everyone 1 day to run down to the assessor's office.)
If your taxes are actually assessed legally now (even though the final due date is 2/28) then you could take a deduction for 2018 by paying them in 2018.
However, you won't get any actual benefit unless your total itemized deductions are more than $12,000 (single) or $24,000 (married filing jointly). Plus, there is a $10,000 cap on deductions for state and local sales tax, income tax and property tax combined.
So you really have to look at your own situation. Assuming you paid your 2018 taxes in February 2018, you might find that paying your 2019 taxes also in 2018 raises your itemized deductions high enough to beat the standard deduction so you get some additional benefit. Then you pay no tax in 2019 and take the standard deduction. Then you pay 2020 taxes in Feb 2020 and your 2021 taxes in December 2020, again doubling your deduction so you get over the standard deduction. But on the other hand, if you double your property tax deduction this year, you might find that your combination of state income tax and 2 years of property tax bumps into that $10,000 cap causing you to lose a potential deduction amount. And if you are married, and even 2 years of property taxes, plus your state income taxes, mortgage interest, and donations to charity, are still less than $24,000 standard deduction, you won't itemize and it doesn't matter when you pay because you will never have enough deductions to itemize.
