I'm in California where we're hit hard by the new $10,000 cap on property tax deductions. My annual property taxes are already $13K. I bought by home in Feb 2017 and paid ~4K in property taxes in 2017 (everything I had been billed for). Then I was hit with a supplemental bill for almost $10K in 2018. With my normal annual property taxes, I have paid more than double what I am allowed to deduct, but half of that is for 2017. This is certainly the worst year for this to happen since, any other year, I could have just deducted the supplement in the year paid. Is there any way to avoid being penalized for only being assessed the supplement in 2018?
If the "supplemental" property tax bill is for isn't actually property tax, but is actually "assessment" to cover the cost of something that the city/state did (such as sewer lines, roads, etc.), that is not part of the deductible property tax anyways.