<prompt> Human: 2018 stateproperty tax deduction capped at 10k. 2017 no cap.  <response>: you can only pre-pay 2018 property taxes if they have been IMPOSED to you during 2017. so a lot of localities are fiscal year instead of calendar year. meaning fiscal year 2018 is actually 712017 - 6302018. and they allow their property owners to pay 4 times a year. FY 18 Q1 would be due 812017, FY 18 Q2 is due 1112017, FY 18 Q3 is due 2118 and FY 18 Q4 is due 5118.So obviously FY 18 Q1 and Q2 count. But FY Q3 and Q4 only count if they were imposed to you during 2017... meaning, did you, or will you, get the Q3 and Q4 bills before 12312017? If yes, you can pre-pay them before 12312017, and then take them on your 2017 taxes.ETA: you cant just go around pre-paying property taxes in 2017 for 2018, 2019, and 2020 with the intent of taking them on your 2017 return. 