Property tax assessment.

In plain English

A property tax assessment is the dollar value a county or city assessor assigns to your home and land, which becomes the base for your property tax bill. The local government multiplies that assessed value (sometimes only a fraction of market value) by a tax rate, often called a mill rate or millage, to set what you owe. Assessed value is not always the same as what your house would sell for, and how it is calculated varies a lot by state and county. If you think your assessment is too high, most places let you file an appeal within a set window.

01Why it matters

Your assessment drives a bill you pay every year for as long as you own the home, so an inflated value quietly costs you money year after year.

02The math, step by step

Suppose your county assesses your home at $250,000 and the combined tax rate is 1.2 percent. Your annual property tax would be about $3,000, or roughly $250 a month inside your escrow. Rates and assessment methods differ widely by state and county, so check your own county assessor's website for your local assessment ratio and tax rate.

03What this is NOT