Where I live (relatively upscale Philly suburb) the absolute magnitudes of the assessments are irrelevant -- all that matters is what your assessment is relative to everybody else. For example, my house is assessed at $93K, but I bought it three years ago for $142K and its current sale estimate is about $215K. Everybody's assessment is way below market value, but what happens is the school board decides what their budget is going to be every year and then they set the millage rate to whatever it needs to be in order to generate that much property tax revenue (the school tax is about 85% of our total property taxes). So it doesn't really matter how up-to-date the assessments are since it won't affect your tax bill.