Real Estate Taxes While You Own: Property Tax, Explained Line by Line
Assessed value times a mill rate, minus exemptions — and every one of those three pieces can be challenged
Open interactive version (quiz + challenge)Real-world analogy
Property tax is like the maintenance charge in an apartment building, except the building is your whole town. Roads, schools, fire service and rubbish collection are the shared corridors. Your share is worked out from a number the town puts on your flat — and like any maintenance bill, it is worth reading how they arrived at your share rather than just paying it.
What is it?
Property tax is an annual ad valorem tax — Latin for 'according to value' — charged by local government on real property. The arithmetic is nearly always the same three steps: an assessor sets an assessed value, local taxing bodies set a rate (often expressed in mills, where one mill is $1 per $1,000 of assessed value), and exemptions are subtracted. IRS Publication 530 describes the deductible kind: "Deductible real estate taxes are generally any state or local taxes on real property levied for the general public welfare."
Real-world relevance
For most owners this arrives inside the monthly mortgage payment, in the escrow portion, which is why so few people ever look at the bill itself. Then the escrow analysis letter arrives, the payment jumps, and the owner discovers the assessment rose 18%. The two moments that matter are the assessment notice — which has a short appeal window, often measured in weeks — and the annual budget hearings where the rate is set. Missing the appeal window means living with the number for a full cycle.
Key points
- Assessed value is not market value — Many jurisdictions assess at a fraction of market value, apply their own valuation cycle, and may reassess only every few years or on sale. A $400,000 house can carry a $260,000 assessed value. Comparing your tax bill to a neighbour's is meaningless without comparing the assessments underneath them.
- A mill is one dollar per thousand dollars of assessed value — A 25-mill rate on a $260,000 assessment is 260 x $25 = $6,500. Your total rate is usually the sum of several separate levies — county, city, school district, sometimes fire or library districts — each set by a different body.
- Exemptions are the cheapest tax cut available and often unclaimed — Homestead exemptions for owner-occupants are the most common, with additional ones in many places for seniors, veterans, and people with disabilities. They are usually applied for once, not automatically. Check your county assessor's exemption page — this is a five-minute task that can pay every year.
- You can appeal the assessment, and the argument is about VALUE not the bill — An appeal succeeds by showing the assessed value is wrong — with recent comparable sales, an independent appraisal, photographs of condition problems, or an error in the recorded square footage or bedroom count. Arguing that the tax is too high, or that you cannot afford it, is not an argument the board can act on.
- ⚠️ Common misconception: 'Property tax is fully deductible on my federal return' — Only if you itemize, and only within the state and local tax (SALT) cap, which limits the combined deduction for state and local income, sales and property taxes. That cap was set at $10,000 by the Tax Cuts and Jobs Act and has since been changed by later legislation — check IRS Publication 530 for the figure that applies to the year you are filing rather than assuming last year's number.
- Mortgage interest has its own separate limit — Under IRS Publication 936, interest is generally deductible on up to $750,000 of home acquisition debt for loans taken after 15 December 2017 ($375,000 if married filing separately). Loans predating that date are generally grandfathered under the older $1,000,000 limit.
Code example
READING A PROPERTY TAX BILL, LINE BY LINE
==========================================
(Structure is near-universal; rates are
local. Use your own bill's numbers.)
STEP 1 - THE VALUE
Market value (assessor's opinion) . $400,000
Assessment ratio (example: 65%) ... x 0.65
ASSESSED VALUE .................... $260,000
STEP 2 - EXEMPTIONS
Homestead exemption ............... -$ 25,000
TAXABLE ASSESSED VALUE ............ $235,000
STEP 3 - THE RATE (sum of the levies)
County ...................... 8.0 mills
City ........................ 6.5 mills
School district ............. 14.0 mills
Fire district ............... 1.5 mills
TOTAL ....................... 30.0 mills
= $30 per $1,000 of value
STEP 4 - THE BILL
$235,000 / 1,000 ................. 235
235 x $30 ........................ $ 7,050/yr
Monthly escrow portion ........... $ 587.50
WHAT AN APPEAL IS WORTH
Suppose comparable sales support a
market value of $360,000, not $400,000.
New assessed: $360,000 x 0.65 .... $234,000
Less homestead ................... -$ 25,000
Taxable .......................... $209,000
New bill: 209 x $30 .............. $ 6,270/yr
SAVED, EVERY YEAR ................ $ 780
For one afternoon of pulling comps.
WHAT AN APPEAL IS NOT
You cannot appeal the mill rate. That is
set in public budget meetings. Different
fight, different room, different date.Line-by-line walkthrough
- 1. STEP 1: the assessor's opinion of market value gets multiplied by the local assessment ratio. This is why your assessed value can look far below what you would sell for — and why the two numbers must never be compared directly.
- 2. STEP 2: exemptions come off the assessed value, not off the final bill. A homestead exemption of $25,000 removes $25,000 of taxable value, worth the exemption times your mill rate.
- 3. STEP 3: the rate is the SUM of several independent levies. Your school district is often the largest single component, which is why school budget votes move property tax bills more than city hall does.
- 4. STEP 4: divide the taxable assessed value by 1,000 and multiply by the total mills. $7,050 a year, or $587.50 a month inside your escrow payment.
- 5. THE APPEAL: if comparable sales support $360,000 rather than $400,000, the same arithmetic produces a $6,270 bill — $780 saved every year, for the work of assembling three comps and filing before the deadline.
- 6. OUTCOME: note precisely what an appeal can and cannot touch. Value is appealable to the assessment board. The mill rate is not — it is decided in public budget hearings, which is a different process on a different calendar.
Spot the bug
Homeowner's reasoning: 'My neighbour's house is nearly the same as mine and their tax bill is $1,400 lower. I will appeal my assessment and show the board my neighbour's tax bill as proof that mine is unfair.'Need a hint?
Ask what the board is actually empowered to change, and what could make two similar houses carry different bills.
Show answer
The neighbour's TAX BILL is the wrong exhibit. An assessment appeal decides whether your assessed VALUE is correct, so the evidence has to be about value: recent comparable sales, an independent appraisal, photographs of condition issues, or a factual error in the record such as wrong square footage or a bedroom that does not exist. A lower bill next door can have several causes that say nothing about your value — the neighbour may hold a homestead, senior or veteran exemption you do not, may sit in a different fire or school district, or may have a stale assessment from an older valuation cycle. Pull the neighbour's ASSESSMENT record instead, compare it against yours, and if it shows a genuine valuation inconsistency on similar properties, that is an argument the board can act on.
Explain like I'm 5
Every year the town works out how much your house is worth, then charges you a small slice of that value to pay for schools, roads and the fire service. If you think their number for your house is too high, you can ask them to look again — but you have to show them houses like yours that sold for less, not just say the bill is big.
Fun fact
The word 'mill' in a mill rate comes from the Latin millesimum, meaning thousandth: one mill is one thousandth of a dollar, so a mill rate of 30 means $30 of tax for every $1,000 of taxable assessed value. It is one of the last places in everyday American life where a Roman fraction still does the arithmetic.
Hands-on challenge
Find your latest property tax bill or your county assessor's online record and write down four things: the market value, the assessment ratio, every exemption applied, and the total mill rate broken into its separate levies. Then check the appeal deadline for your county and put it in your calendar with a two-week warning. Most people never learn this deadline until it has passed.