The three moving parts
1. Assessed value. The county assessor assigns your home a value. Some states assess at full market value; others use a fraction — Michigan taxes a “taxable value” capped at 50% of market value, and Cook County, Illinois assesses residential property at just 10%. This ratio is why comparing raw “rates” across states is meaningless without knowing what the rate is applied to.
2. Exemptions. Most states knock something off before taxing. Texas takes $100,000 off school-district taxable value for a homestead; Florida offers up to $50,000; some states give a rate reduction instead of a dollar amount. Seniors, veterans and disabled homeowners often get more. Exemptions usually require an application — they are not automatic, and unclaimed exemptions are one of the most common ways homeowners overpay.
3. The rate. Your total rate is a stack of overlapping levies: county, city, school district, and special districts (community college, hospital, flood control). School districts are typically the biggest slice. This stacking is why two houses a mile apart, in the same county but different school districts, can pay meaningfully different bills.
A worked example
Say a $400,000 home in a state with a 50% assessment ratio, a $25,000 exemption, and a combined 2.1% millage on taxable value: $400,000 × 50% = $200,000 assessed; minus $25,000 = $175,000 taxable; × 2.1% = $3,675 per year, about $306 a month escrowed into your mortgage payment.
What you can actually control
You can’t vote your school levy down single-handedly, but you can: claim every exemption you qualify for, check the assessor’s record for factual errors (wrong square footage is common), and appeal an assessment that’s out of line with comparable sales. Those three levers are where real money is saved.