How to read your property tax assessment and appeal it

That envelope from the county that looks like junk mail isn't junk mail. It's your notice of assessed value, and somewhere on it, usually in small type near the bottom, there's a deadline. In a lot of counties it's 30 to 45 days from the mailing date. Miss it and you're done for the year. Not "done, but they'll make an exception." Done.

So open it. Today.

The other thing worth knowing up front: you can't appeal your tax bill. You can only appeal the value the assessor put on your property. The rate is set by the school district, the county, the city, the fire district and whoever else has taxing authority, and none of them care about your opinion at a value hearing. Show up complaining that taxes are too high and you'll get a polite nod and a denial.

How the bill is actually built

Four numbers, in order.

Market value. What the assessor thinks your property would sell for as of a specific date. In many states that date is January 1, which means a sale from last March is more relevant than one from last week.

Assessed value. Some states tax the full market value. Others apply an assessment ratio, so a $300,000 house might be assessed at 10 percent, or 40 percent, or 100 percent. This is the number that trips people up when they move across state lines and see "assessed value: $30,000" and assume they won the lottery.

Exemptions. Subtracted from the assessed value to get taxable value.

The rate. Often expressed in mills. One mill is one dollar of tax per $1,000 of taxable value, so 21 mills is 2.1 percent.

Worked example, illustrative only, not anybody's real numbers: a house assessed at $300,000 in a state with a 100 percent ratio, a $50,000 homestead exemption, and a combined rate of 21 mills. Taxable value is $250,000. Tax is $5,250 for the year. Knock the assessed value down to $270,000 on appeal and you're at $4,620. That's $630 you keep, every year, until the next reassessment.

Rates, ratios, exemption amounts, deadlines and appeal bodies all vary by state and by county. Some counties reassess every year, some every three, some every five, and a few are so far behind that the "current" value on file predates the last remodel on your street.

The assessor has never seen your house

Understand this and half the process makes sense. Most residential assessment is mass appraisal. A computer model takes square footage, lot size, year built, bathroom count, garage, basement, pool, and neighborhood sales, and spits out a value for every parcel at once. Nobody walked your hallway. Nobody knows the foundation is cracked.

Which means the source data is often wrong, and the fastest win in this whole game is finding an error.

Go to the assessor's website and pull your property record card. It's public. It lists everything the county thinks it knows about your parcel. Check:

• Square footage of finished living area. Is the unfinished basement being counted as finished?
• Bathroom count. Half baths are frequently logged as full.
• Lot size and acreage against your deed or survey.
• Year built, and whether a "remodel year" got entered for a permit you pulled to replace a water heater.
• Features you don't have. Fireplaces, pools, central air, a second garage bay, a porch that got torn off in 2014.

I've seen a record card list a detached shop that burned down before the current owner was born. Nobody catches these but you.

Claim every exemption before you argue about value

Exemptions are the easier money, and people leave them on the table constantly. The common ones, and again, availability and amounts vary enormously by state:

• Homestead. Your primary residence. In some states it also caps how fast your assessed value can rise year to year, which is worth more over a decade than the exemption itself.
• Senior or over-65. Sometimes an exemption, sometimes a freeze on the assessed value or on the school portion.
• Disabled veteran. In several states a service-connected rating at certain levels wipes out the property tax entirely on a homestead. This one is life-changing and criminally under-claimed.
• Surviving spouse. Often tied to veterans or first responders.
• Agricultural, timber, wildlife or open space. For landowners, these value the land on its productive use rather than its development potential. The tax difference can be an order of magnitude.

Two traps. First, when you buy a house, the seller's exemptions usually don't come with it. You have to re-file, and the tax bill you looked at during due diligence may have been an old man's frozen, homesteaded, senior-exempt bill that's about to double in your name. Ask your closing attorney or title agent to run the number as if you owned it.

Second, ag exemptions often carry rollback taxes. Change the use of the land, subdivide it, build on it, and the county can bill you the difference between ag value and market value for the past three to five years, plus interest, all at once. Know that before you close on acreage.

Building an appeal that wins

You need evidence, and there are two arguments that work.

Overvaluation. Comparable sales say your property is worth less than the assessed value. Pull three to five sales of genuinely similar homes, same neighborhood, same style, similar size and age, that closed near the assessment date. Adjust honestly for differences. An agent will usually pull a comp set for you at no charge, and a full appraisal runs a few hundred dollars if the stakes justify it.

Uniformity. Your neighbors with nearly identical houses are assessed lower. This one wins a lot and costs nothing but time on the assessor's parcel search. Screenshot the record cards.

Then add condition evidence the model couldn't see. Dated photos of the failing roof, the cracked slab, the original 1978 kitchen, the drainage that floods the back third of the lot. Bring the contractor's written estimate, not a guess.

What loses: "my taxes went up 18 percent." "I'm on a fixed income." "The house across town is nicer." And the worst one, appealing the year after you paid $415,000 for a house now assessed at $390,000. Your own closing statement is the best comp in the room, and it's pointed at you.

The order it actually happens

Start with the informal review. Call or email the assessor's office, ask for a review, send your evidence. It's free, it's fast, and a clear factual error often gets corrected in a phone call. Most people skip this step and go straight to a hearing they didn't need.

If that fails, file the formal appeal with the board of review, board of equalization, or value adjustment board, depending on your state. Filing fees are often modest or nothing. Deadlines are absolute.

The hearing itself is short. Figure 10 to 15 minutes in front of three people who've heard forty of these already. Bring a stapled packet, one copy per board member plus one for the assessor's rep. Lead with your number. "The assessment is $340,000. The evidence supports $298,000. Here's why." Then walk through comps, then errors, then condition. Be pleasant. The assessor's representative isn't your enemy and is frequently the person who agrees to a settlement in the hallway before you ever go in.

Lose there and you can usually appeal to a state tax tribunal or circuit court, which is where lawyers come in. Property tax firms often work on contingency, commonly a share of the first year's savings. Read that agreement closely, especially whether the fee is based on one year or several.

After you win

The refund doesn't arrive the way you expect. If you escrow, the correction flows through your servicer's annual escrow analysis, and your payment adjusts on their schedule, not yours. Sometimes months later. Call the servicer and ask them to re-run the analysis once the county issues the corrected bill.

And calendar next year's notice date now. Assessments reset. The win isn't permanent.

None of this is legal, tax or financial advice for your situation. Rules on deadlines, exemptions, rollbacks and appeal rights change across state and even county lines, so run your specifics past a licensed real estate attorney, a CPA, or your county assessor's office before you act.

The county mailed you a number somebody's software made up. You're allowed to disagree in writing.