The grounds for a property tax appeal fall into two categories: overvaluation, meaning your assessed value is higher than what the property would sell for, and unequal assessment, meaning your property is taxed at a higher ratio of market value than comparable properties around it. Both are rooted in constitutional protections, both can produce real tax reductions, and each demands a different kind of proof. Which one fits your situation determines everything about how you build the case.
Overvaluation
An overvaluation appeal argues that the assessor set your property’s value higher than a knowledgeable buyer would pay a knowledgeable seller, with neither side under pressure to close. If your assessment says $450,000 and comparable homes in your area are selling for $400,000, the tax bill rests on a number the market doesn’t support.
The detail that sinks most overvaluation appeals is the date. Market value is measured as of a specific assessment date, sometimes called the valuation date. A property might have been worth the assessed amount a year ago and no longer be worth it today, but the appeal turns on what the property was worth on that particular date. Owners who bring current listings or recent sales that fall outside the relevant window often lose on evidence that would have won with better timing.
This ground focuses on your parcel alone. You are not comparing yourself to your neighbors. You are saying the official value is higher than the economic value, whether because the market shifted, the property has physical problems, or the assessor missed something. It is a clean factual claim, and it stands or falls on your own numbers.
Unequal Assessment and the Uniformity Requirement
Unequal assessment is a different argument, and it catches owners off guard because it can succeed even when your dollar-figure assessment is technically accurate. The principle is equity. If your jurisdiction assesses residential properties at roughly 80% of market value, every home in that class should be assessed at roughly 80%. When yours is assessed at a higher percentage than your neighbors’, the tax burden is distributed unfairly regardless of whether your assessed number matches your home’s actual sale price.
The Fourteenth Amendment’s Equal Protection Clause prohibits states from applying their tax laws in ways that systematically discriminate between similarly situated owners. In Allegheny Pittsburgh Coal Co. v. Webster County Commission, a county assessor valued recently sold properties at their purchase price while barely adjusting neighboring parcels that hadn’t changed hands, producing assessment ratios that varied by as much as 35 to 1. The U.S. Supreme Court held that the Equal Protection Clause requires assessment adjustments to achieve rough equality among comparable properties within a reasonable time frame.1Legal Information Institute. Allegheny Pittsburgh Coal Co. v. Webster County Commission, 488 U.S. 336
The remedy comes from an earlier decision, Sioux City Bridge v. Dakota County: an owner facing discriminatory assessment is entitled to have their assessment reduced to the common level rather than being made to wait while the government raises everyone else’s.2Legal Information Institute. U.S. Constitution Annotated – Amendment 14 Section 1 – Property Taxes Your appeal board should bring your assessment ratio down to match the average ratio applied to comparable properties.
Building this case takes two numbers. First, your own assessment ratio, which is your assessed value divided by your property’s market value. Second, the average ratio for comparable homes nearby. If your home sits at 95% of market value while the neighborhood average sits around 75%, you have a uniformity argument even if the $450,000 on your notice is exactly what the house would sell for.
Which Ground Fits Your Situation
The two grounds are not mutually exclusive. Most jurisdictions allow you to raise both in the same appeal, and many owners do. The question is which one your evidence actually supports.
If your assessed value is out of step with recent sales of similar homes, overvaluation is your argument. If your assessed value roughly matches what your home would sell for but your neighbors’ assessments run noticeably lower relative to their market values, uniformity is your argument. If both are true, plead both.
A separate diagnostic step sits underneath either ground: request your property record card from the assessor’s office and check it for factual errors. Square footage inflated by exterior measurements, a single-story home recorded as two stories, a finished basement that doesn’t exist, wrong bedroom or bathroom counts, or an incorrect year of construction can all push an assessment up. A record card error is not itself a legal ground, but it is often the fastest fix, and many assessors will correct obvious mistakes informally without any hearing.
The Evidence Each Ground Requires
For Overvaluation
A professional appraisal from a state-certified appraiser is the strongest piece of evidence. It should be dated as close to the assessment date as possible and comply with the Uniform Standards of Professional Appraisal Practice. Most appeal boards give little weight to opinions of value from real estate agents, who aren’t trained in the same methodology. A standard single-family residential appraisal generally runs $300 to $600, with complex or high-value properties costing more. Estimate your potential tax savings before you commit to that expense.
With or without an appraisal, gather comparable sales. Comps should match your property in size, age, condition, and location, and they should have closed in the six to eighteen months before the assessment date, though the acceptable window varies. Three to five strong comps carry more weight than a dozen weak ones. When a comparable differs from your property in a meaningful way, be ready to explain the adjustment. A comp that sold for $380,000 with a two-car garage supports a value below $380,000 for your home if yours has a one-car garage.
Document physical problems the assessor didn’t account for. Foundation cracks, outdated electrical panels, roof damage, mold, and flood damage all reduce market value. Photographs help, but written repair estimates from licensed contractors are more persuasive because they give the board a dollar figure. Boards often call this “cost to cure” evidence: how much would it take to bring the property up to the condition the assessor apparently assumed?
For Uniformity
You need assessed values and estimated market values for comparable properties in your area. Assessed values are public records, available through the assessor’s office or website. Market values take more work. You can use recent sale prices for properties that sold near the assessment date, or apply standard valuation techniques to properties that haven’t sold. The end product is a table showing that your assessment ratio meaningfully exceeds the average ratio for your peer group. Boards will not build that table for you.
The Burden of Proof Sits With You
This is where most appeals are won or lost. In nearly every jurisdiction, the assessor’s valuation carries a presumption of correctness. The board starts from the assumption that the assessor got it right, and the owner has to prove otherwise.
For overvaluation, you typically need to show by a preponderance of the evidence, meaning more likely than not, that the assessed value exceeds fair market value. A credible independent appraisal and a handful of strong comparable sales can meet that standard. Assertions that “the market is down” or that a neighbor’s house sold for less will not, without data behind them.
For uniformity, the burden shifts slightly in your favor once you demonstrate a meaningful disparity in assessment ratios. But you still have to calculate and present those ratios. Boards do not investigate on your behalf, and an owner who walks in with a general complaint about fairness loses regardless of how right the complaint is.
One warning worth taking seriously: the board is not limited to choosing between your number and the assessor’s. It can set any value the evidence supports, which occasionally means an owner leaves with a higher assessment than they started with. This is uncommon, but it is a real reason not to file a weak case.
Deadlines and the Informal Review
Most jurisdictions set formal appeal deadlines of 30 to 90 days after you receive your assessment notice, and those deadlines are enforced strictly. Miss the window and you are locked into that value for the tax year with no recourse.
Before the formal appeal, most jurisdictions offer an informal review, and skipping it is one of the more common mistakes owners make. An informal review is a conversation with the assessor or a staff member where you share your evidence. There is no board and no formal record. Assessors would rather fix a legitimate error at their desk than defend it at a hearing, and these conversations resolve more disputes than most people expect. Even when the informal review doesn’t produce a change, you leave knowing what the assessor is relying on, which is useful preparation for the formal hearing.
If a Business Entity Owns the Property
If the property is held by an LLC, corporation, or partnership rather than in your personal name, check your jurisdiction’s rules on representation well before the hearing. A number of states require business entities to be represented by a licensed attorney at formal appeal hearings, on the theory that an entity acts only through authorized representatives. Some states allow officers, managing members, or employees with written authorization to appear without counsel, but the rules vary enough that getting this wrong can get your appeal dismissed before the board looks at your evidence. This catches small landlords and real estate investors more than almost any other procedural issue.
Check Exemptions and Abatements First
Before investing time in an appeal on either ground, verify that you are claiming every property tax exemption and abatement you qualify for. Homestead exemptions for owner-occupied residences, senior freezes or deferrals for homeowners over 65, exemptions for veterans with service-connected disabilities, and abatements for damaged or contaminated properties exist in some form across most of the country. Veteran exemptions can be substantial, sometimes eliminating the tax entirely at high disability ratings. Exemptions and appeals are not mutually exclusive, so you can pursue both at once, but if an exemption alone solves the problem, you avoid the work of building an evidentiary case.