Property tax is calculated by multiplying your home’s assessed value by the combined millage rate of every local taxing body that covers your parcel, then subtracting any exemptions you qualify for. There is no federal property tax; counties, cities, school districts, and special-purpose districts set the rates and send the bills. Understanding how property tax is calculated comes down to two numbers the local government assigns to your home, plus a short list of adjustments that can lower what you owe.
The Two Numbers That Drive Your Bill
Every property tax bill in the United States starts from the same equation: assessed value times tax rate. Everything else is an adjustment to one side or the other.
Assessed Value Versus Market Value
A local assessor determines your property’s fair market value, which is the price a willing buyer would pay in an open market. In many jurisdictions the taxable assessed value equals the full market value. In others, local rules set the assessed value at a fraction of market value, sometimes as low as 10% or as high as 90%.
The ratio matters enormously. A home with a $400,000 market value assessed at 100% is taxed on $400,000. The same home in a jurisdiction using a 50% assessment ratio is taxed on $200,000. Before you compare tax rates between two areas, you need to know the assessment ratio each one uses, because a low rate applied to full value can produce a higher bill than a high rate applied to half value.
Millage Rates
Once the assessed value is set, the local government applies a millage rate. One mill equals one dollar of tax for every $1,000 of assessed value. If your home’s assessed value is $300,000 and the combined millage rate from all overlapping taxing bodies is 20 mills, your annual tax is $6,000.
The word “combined” is doing real work there. A single parcel typically falls under four or five taxing bodies at once: a county, a city or town, a school district, and one or more special districts for things like libraries, parks, or fire protection. Each sets its own millage, and the county usually consolidates everything into a single bill. That stacking is why two homes with identical market values in different parts of the same metropolitan area can carry very different tax bills. Rates also move when local governments adopt new budgets, pass bond measures, or adjust levies for schools and infrastructure.
Averaged across the country, the effective tax rate on a single-family home runs roughly 0.9%, which works out to about $4,400 per year on a median-priced home. Your actual rate can be a fraction of that or several times higher.
When Your Assessed Value Changes
Your assessed value is not a fixed number. The most common trigger for a change is a scheduled reassessment cycle, and those cycles vary widely by jurisdiction, anywhere from every year to every six years or longer.
Between scheduled cycles, certain events can trigger an individual reassessment:
- Selling the property, where the new sale price often becomes the updated value.
- Completing major renovations or additions.
- Obtaining building permits for new construction.
- Inheriting a home.
Market-wide swings also feed into the next scheduled revaluation, which is why homeowners in rapidly appreciating neighborhoods see their tax bills climb even when they haven’t touched the property. Falling markets work the same way in reverse, though assessors often lag behind sharp downturns, leaving homeowners paying taxes on a stale, inflated value until the next cycle catches up.
Exemptions That Reduce the Taxable Value
Most states offer property tax relief for homeowners who meet specific criteria. The names and dollar amounts differ, but a few categories appear in nearly every state.
- Homestead exemption: Reduces the taxable value of a primary residence. Some jurisdictions subtract a flat dollar amount from the assessed value; others cap how much the assessed value can rise each year. Eligibility generally requires that you live in the home as your main residence.
- Senior exemptions: Available to homeowners above a certain age, often 65. Some programs freeze the assessed value so it stops rising; others provide an additional deduction on top of the homestead exemption.
- Veteran and disabled veteran exemptions: Veterans with service-connected disabilities often qualify for partial or full exemptions, with the benefit size tied to the disability rating.
- Disability exemptions: Homeowners with qualifying disabilities may receive reductions similar to the senior exemption, sometimes regardless of age.
None of these are automatic. You have to apply through the local assessor’s office and provide proof, such as a driver’s license showing the property address, a DD-214 for veteran status, or documentation of age or disability. Miss the application deadline and you lose the benefit for that tax year. Many jurisdictions also offer deferral programs that let qualifying seniors or low-income homeowners postpone payment until the home is sold, with the deferred taxes recorded as a lien against the property.
Charges on the Same Bill That Aren’t Based on Value
Your tax bill may include charges that have nothing to do with your home’s assessed value. These non-ad valorem assessments fund specific services or infrastructure tied to your parcel: street lighting, stormwater management, trash collection, road improvements, or community maintenance. They’re calculated per parcel or per benefit received rather than as a percentage of value.
Community development districts and special assessment districts are the most common sources. Homeowners in newer subdivisions frequently find substantial annual assessments that fund the roads, utilities, and common areas the developer built, sometimes adding $1,000 to $3,000 per year on top of the regular property tax. These are often repaid over 10 to 30 years and carry their own lien. Property Assessed Clean Energy (PACE) financing for energy-efficient upgrades or storm-hardening improvements can also appear as a line item, secured by a lien that survives a sale.
Because these charges ride on the same bill, they’re easy to overlook. Before buying a home, review the full tax bill, not just the ad valorem portion. A low millage rate means little if special assessments double the total.
Appealing an Assessment You Think Is Too High
If the assessed value looks too high, you can challenge it, and most homeowners who file with decent evidence get at least a partial reduction.
The process generally works in stages. After receiving your assessment notice, you have a limited window to file a formal protest, typically 30 to 45 days depending on your jurisdiction. Missing that deadline usually means waiting until the next cycle. Some areas require you to contact the assessor’s office for an informal review first, which can resolve obvious errors without a hearing.
If the informal route fails, you file a written appeal with the local board of review or equalization. The burden of proof falls on you. The strongest evidence tends to be:
- Recent sale prices of similar homes in your neighborhood that sold for less than your assessed value.
- Errors in the property record, such as incorrect square footage, an extra bathroom that doesn’t exist, or a finished basement listed when yours is unfinished.
- An independent professional appraisal showing a lower market value. This costs a few hundred dollars and only makes sense for larger discrepancies.
- Photos of structural problems, deferred maintenance, or other condition issues that pull the real value below what comparable sales suggest.
If the local board denies the appeal, most states offer a secondary level of review through a state-level board or tax court. That stage is more formal, sometimes requiring sworn testimony and compliance with rules of evidence. For most homeowners, the local hearing is where the matter is decided.
Deducting What You Paid on Your Federal Return
Property taxes paid on your home are deductible on your federal income tax return, but only if you itemize on Schedule A rather than taking the standard deduction. To qualify, the tax must be based on property value, levied uniformly across the community, and used for general government purposes. Special assessments for neighborhood improvements like sidewalks or sewer lines usually don’t qualify.1Internal Revenue Service. Publication 530 (2025), Tax Information for Homeowners
Your federal deduction for state and local taxes combined, including property taxes, state income taxes, and sales taxes, is capped at $40,400 for the 2026 tax year ($20,200 for married filing separately). Legislation passed in 2025 raised the cap from the previous $10,000. It increases by 1% annually through 2029 and is scheduled to drop back to $10,000 in 2030.2Office of the Law Revision Counsel. 26 USC 164 – Taxes
An income-based phasedown applies: the full $40,400 deduction begins shrinking for taxpayers with modified adjusted gross income above $500,000 ($250,000 for married filing separately).3Internal Revenue Service. Instructions for Schedule A (Form 1040) If your mortgage lender pays property taxes from an escrow account, you deduct only the amount the lender actually paid to the taxing authority during the year, not the total you deposited into escrow.1Internal Revenue Service. Publication 530 (2025), Tax Information for Homeowners