Millions of homeowners are opening their county assessment notices this spring and finding a number that doesn't match what they thought their house was worth.
In many metro areas, assessed values jumped double digits even as the housing market cooled and mortgage rates hovered near 7%.
The result: a tax bill that can run hundreds or even thousands of dollars above last year, arriving in the same season as rising insurance premiums and grocery bills.
It's an opinion, and counties almost never check whether it's right.
Roughly 30 to 60 percent of properties are over-assessed, according to appraisal industry estimates, often because the county's data is stale, the square footage is wrong, or the model compared your house to sales from a different neighborhood.
You usually have a short window to push back.
In most states, the appeal deadline is 30 to 90 days from the notice date, and missing it means waiting a full year.
The process is free, doesn't require a lawyer, and a meaningful share of appeals succeed.
Some counties report that a third to half of formal challenges result in a reduction.
Start by pulling your property record card from the county assessor's website.
Check the basics: bedrooms, bathrooms, square footage, lot size, and year built.
Errors here are common and easy to document with a tape measure and a copy of your deed.
Then find three to five recent sales of similar homes in your neighborhood.
If those homes sold for less per square foot than your assessed value, you have a case.
First, request an informal review before filing a formal appeal.
Many assessors will correct obvious mistakes over the phone or at a counter without a hearing.
Second, if you've had a recent appraisal for a refinance, that document carries weight, especially if it's lower than the county's number.
Watch for the trap of a big homestead exemption you forgot to file.
In states like Florida, Texas, and Georgia, exemptions can shave thousands off the taxable value, and some counties don't apply them automatically after a purchase.
A quick call can fix a year of overpayment.
Don't count on a national crash in assessments to bail you out.
Many counties lag the market by a year or two, so even where prices have dipped, notices may still climb.
Budget for the increase now, and if you escrow your taxes, expect your monthly mortgage payment to adjust upward at the next escrow analysis.
Our take: the system rewards people who show up, and most homeowners never do.
Spending an hour with your record card and three comparable sales is one of the highest-return chores available to a household this year.
Final Thoughts
If your notice looks wrong, file before the deadline, because the county won't do it for you.