Your property tax bill is calculated by multiplying your home's assessed value by the local tax rate. If your assessed value is $350,000 and the tax rate is 1.2%, you pay $4,200 per year. But what if your home is actually worth $310,000? You'd be overpaying by $480 per year — every year, until you appeal. Over 10 years, that's $4,800. Over the time you own the home, the overpayment compounds as assessments use the inflated baseline for future increases.
Studies show that 30–60% of all properties in the United States are over-assessed. Yet fewer than 5% of homeowners ever appeal. The process is straightforward, free (or very inexpensive), and has a surprisingly high success rate: 30–40% of appeals result in a reduction, with an average annual savings of $1,000–$3,000.
County or municipal assessors determine your property's assessed value, typically every 1–3 years (the schedule varies by state and county). They use mass appraisal techniques — computer models that estimate values for thousands of properties at once based on property characteristics (size, age, lot size, location) and recent sales data.
Mass appraisal is efficient but inherently imprecise. The assessor's model doesn't know that your basement floods every spring, that the house next door has a barking dog that deters buyers, or that your kitchen hasn't been updated since 1985. It applies broad statistical patterns to individual properties, and individual properties are quirky.
In some states, the assessed value equals the estimated market value. In others, assessed value is a percentage of market value (for example, Georgia assesses at 40% of market value). Make sure you understand your state's assessment ratio before comparing your assessed value to market data.
Your assessed value is public information. Find it on your county assessor's website — search by your address or parcel number. While you're there, verify that the property details are correct. The assessor's records should show your home's square footage, number of bedrooms and bathrooms, lot size, year built, and condition rating.
Errors in property details are the easiest appeals to win. If the assessor has your home listed as 2,200 square feet when it's actually 1,900 square feet, or counts a finished basement that's actually unfinished, or lists 4 bedrooms when you have 3 — that's a factual error that directly inflates your assessment. Check every detail against your actual home.
The most effective appeal strategy is demonstrating that comparable homes ("comps") sold for less than your assessed value. Pull recent sales (within the last 6–12 months) of homes similar to yours within 0.5 miles. Focus on homes with similar square footage (within 10%), similar age (within 10 years), similar lot size, and the same number of bedrooms and bathrooms.
Use Zillow, Redfin, or Realtor.com to find recent sales, then cross-reference with your county's property records for the official sale price. You need 3–5 strong comps. Calculate the average sale price per square foot and apply it to your home's square footage. If your comps averaged $155/sq ft and your home is 1,900 sq ft, the indicated value is $294,500. If your assessment is $350,000, you have a strong appeal.
Also look at the assessed values of similar homes on your street and in your neighborhood. If your neighbor's identical home is assessed at $310,000 while yours is assessed at $350,000, that's evidence of unequal treatment — another valid basis for appeal in most jurisdictions.
Beyond comparable sales, document any condition issues that affect your home's value but might not be captured in the mass appraisal model. Examples include: a busy road or highway adjacent to your property, deferred maintenance (aging roof, outdated systems), environmental issues (flood zone, contaminated soil nearby), structural problems (foundation cracks, settling), functional obsolescence (unusual floor plan, too few bathrooms for the bedroom count), and external factors (cell tower nearby, commercial property abutting your lot).
Photographs are powerful evidence. Take clear photos of any negative conditions — water damage, cracked foundation, peeling paint, busy road view — and include them in your appeal file. Assessors respond to visual evidence more than verbal descriptions.
Most jurisdictions offer an informal review process before the formal appeal. Call your county assessor's office and request an informal review or "assessment consultation." This is typically a phone call or in-person meeting where you present your evidence to an assessor and they can adjust your value without a formal hearing.
Informal reviews resolve a surprising number of cases — especially when the issue is a factual error (wrong square footage, incorrect property details). Many assessors will correct obvious errors on the spot. Bring your comparable sales data even to the informal review — if your evidence is strong, the assessor may reduce your value without requiring a formal appeal.
If the informal review doesn't resolve the issue, ask about the formal appeal deadline. In most jurisdictions, you have a window of 30–90 days after receiving your assessment notice to file a formal appeal. Missing this deadline means waiting until the next assessment cycle.
Formal appeals go before a Board of Review, Board of Equalization, or Assessment Appeals Board (the name varies by jurisdiction). You'll present your case at a hearing — typically 15–30 minutes. Many boards allow you to submit evidence in writing and attend by phone or video.
Your presentation should include: your property's current assessed value and the value you believe is correct, 3–5 comparable sales with photos and data, a summary showing how the comps support a lower value (average price per square foot applied to your property), documentation of any errors in the assessor's property records, photos of any condition issues that negatively affect value, and the assessed values of comparable neighboring properties (if they're lower than yours).
Dress professionally, be respectful, and be concise. Board members hear dozens of cases per day. Lead with your strongest evidence — comparable sales — and don't ramble. State your requested value, present your comps, and explain why your assessment should be reduced.
If the board reduces your assessment, your property taxes are recalculated based on the new value. The reduction typically applies to the current tax year and carries forward until the next reassessment. On a $40,000 assessment reduction with a 1.2% tax rate, you save $480/year. If the next reassessment is in 3 years, that's $1,440 total savings from a single appeal.
If you lose, you generally have the right to appeal further — typically to a state tax court or administrative body. However, further appeals involve more time, complexity, and sometimes attorney fees. For most homeowners, the informal review and first formal appeal are sufficient.
Important: your appeal cannot increase your assessment. Many homeowners fear that appealing will draw attention and lead to a higher assessment. By law, filing an appeal cannot result in a value increase in the vast majority of jurisdictions. The worst outcome is that your current value stays the same.
The best times to appeal are: immediately after a significant assessment increase (more than 10% in a single year), when comparable sales clearly show a lower value (market downturn, local issues), when you discover an error in your property records, after significant damage or condition decline that hasn't been reflected in the assessment, and when neighboring comparable properties have noticeably lower assessments.
Don't appeal if your assessment is accurate or below market value. Some homeowners have assessments below actual market value — appealing would only draw attention. Check whether your assessment is reasonable before filing.
Property taxes are one of the largest ongoing costs of homeownership. Browse our property tax rates by state at /states to see where your state ranks, and explore our city-level property tax data to understand local rates. A few hours spent on an appeal can save you thousands over the life of your ownership.