Why new homeowners should check their property tax assessments

[UNITED STATES] If you've recently purchased a home, it may be a smart time to take a closer look at your property tax assessment, experts advise.

Property tax assessments are used by local governments to determine the taxable value of your home. But when those assessments are based on outdated or incorrect information, you could end up paying more than you should.

In many areas, tax assessors rely on mass appraisal systems, which don’t always capture the unique characteristics of individual properties. A house with structural damage or aging systems, for instance, might still be valued similarly to a recently renovated home in the same neighborhood. That’s why new homeowners are encouraged to verify the information used to assess their property.

“If there’s an error, you probably already have the documents needed to challenge it,” said Sal Cataldo, a real estate attorney and partner at O’Doherty & Cataldo in Sayville, New York.

Cataldo pointed out that a title report will typically list the home's age, while home inspection reports can highlight any issues with the property. In addition, buyers often have access to appraisals and mortgage documentation that reflect both the market value of the home and nearby comparable sales.

“You’ve collected a lot of information about your property—whether you realize it or not,” Cataldo said.

Appealing an inaccurate assessment doesn’t always take long, but timelines vary. Some municipalities allow appeals within 30 to 90 days of receiving your notice, while others offer only a short window once a year. Miss the deadline, and you may have to wait another year to contest the valuation.

Typically, a home purchase triggers a reassessment based on the new market value, but how and when this is applied depends on local rules.

Why Now Is a Good Time to Review Your Assessment

As a homeowner, your budget likely already accounts for mortgage payments, insurance, and upkeep. Property taxes are another major piece of that financial puzzle.

In recent years, property taxes have been on the rise, driven by increasing home values and adjustments to tax rates.

Municipalities often depend on these taxes to fund public services like schools, road maintenance, and emergency services. Even if home prices level off, rising tax rates can lead to larger bills for homeowners.

According to a report from Realtor, the median U.S. property tax bill in 2024 reached $3,500—a 2.8% increase from $3,349 in 2023.

But costs vary significantly depending on location. LendingTree data shows that in 2023, New York City had the highest median property tax bill in the country at $9,937. San Jose, California, followed closely at $9,554, with San Francisco next at $8,156.

Errors Could Be Inflating Your Bill

Over-assessments are more common than many homeowners realize, according to Pete Sepp, president of the National Taxpayers Union Foundation (NTUF).

“It pays to check,” Sepp said, noting that small mistakes—like an extra bathroom or an incorrect lot size—can significantly affect your tax bill over time.

Some assessments rely on automated valuation models that pull from recent home sales but may overlook specific features or conditions. Often, homeowners can correct inaccuracies with a simple appeal, sometimes without needing professional help.

In many cases, property details may never have been properly updated—such as the actual number of bathrooms or square footage of livable space.

The NTUF estimates that between 30% and 60% of U.S. properties may be over-assessed, based on state-level reports.

Successful appeals can lead to lower tax bills for years, depending on how often your locality reassesses properties. While some do so annually, others may go years between evaluations—or have no regular schedule at all.

Nationwide, more than 40% of homeowners could save $100 or more per year by appealing their assessments, with median savings of $539 annually, according to Realtor.com.