secret home – In roughly a dozen nondisclosure states, final home sale prices don’t appear in public records. Experts say that missing information can leave tax assessors guessing, increase the chance of valuation errors, and create an uneven playing field—potentially lower
On paper, property taxes are supposed to be tied to what a home is worth. In practice, though, the value officials use depends on what sale information is available.
In about a dozen U.S. states—those that keep final transaction prices confidential—home sales can happen without the public ever seeing the number. When sale prices don’t become public record. tax assessors lose one of their most important tools for estimating market value. and experts say the result can be a murky system where transparency and fairness don’t always line up.
“Property taxes are typically imposed by reference to a property’s assessed value. and jurisdictions use different methods and data points to determine what that value is. ” Assaf Harpaz. Assistant Professor at the University of Georgia School of Law. said. “However. when a property is sold off-market. a transparency issue can arise that can affect assessments. given that there are fewer publicly available data points to inform both assessors and potential homebuyers in the area. ” he added.
The way the market gets recorded matters. Home sales are normally followed by filings—deeds and transfer taxes with the county recorder—so the final sale price becomes part of public record in most states. Private listings, while legal in all 50 states, are handled differently at the state level.
In the nondisclosure states, final sales prices are “strictly confidential” and “do not become public record,” Harpaz said. That means assessors may have fewer facts to work with. and potential buyers. researchers. and even potential assessors can’t verify comparable prices the way they might elsewhere.
For Harpaz, the problem is not just that information is missing—it’s that the missingness may benefit people who have access to it.
“Institutional. sophisticated. and wealthy actors may have a greater ability to take advantage of the lack of publicly available information. or to use the information they have. which is not public (e.g. closing statements). to protest an assessment. for example. ” Harpaz said. “That reduced transparency can make assessments less accurate and potentially more favorable to those with superior access to market data.”.
Tax assessors left to guess what homes sold for
Sergio Garate. a real estate researcher at Emory University. has studied this imbalance and published a study on the topic with colleagues in 2025. His conclusion: when private listings keep transaction prices from public view. the knowledge gap can produce real consequences for homeowners and buyers.
Garate said tax assessors in nondisclosure states must rely more heavily on alternative sources of information. including prior assessments. comparable sales. property characteristics. and sometimes the most recent listing price. If even those signals are incomplete—if the assessor lacks both the actual transaction price and a full public listing history—Garate said the valuation process becomes harder and the risk of errors rises.
“If both layers of information are missing, the assessor has less market evidence to work with. That makes the valuation process more difficult and increases the likelihood of errors in the assessment,” he explained.
Those errors can cut in different directions depending on who has the incentive and leverage to challenge an assessment. Garate said property owners can challenge an assessment they believe is too high, but they usually have no incentive to challenge an assessment that is too low.
“Therefore, when missing information leads to more valuation errors, some owners may benefit from underassessment,” Garate concluded. “In that sense. private listings could contribute to lower property tax assessments. especially in nondisclosure states where assessors already face limited access to transaction data.”.
Garate also pointed to a broader mismatch between disclosure and nondisclosure markets, arguing that differences in what information reaches buyers, sellers, assessors, lenders, and researchers can create inequality.
“This imbalance ‘can create inequality between disclosure and nondisclosure states or markets, mainly because the information available to buyers, sellers, assessors, lenders, and researchers differs,’” Garate said.
His research, he said, found evidence that differences in disclosure laws affect appraisals and mortgage performance. Nondisclosure states, Garate and his colleagues found, show stronger rates of appraisal bias and a higher mortgage default probability for the most financially constrained borrowers.
Garate said those information gaps may also affect who can transact and how bargaining power is distributed among brokers and the other parties involved in a real estate deal.
In theory, the private-sale system could mean the tax burden doesn’t fall evenly
The most immediate concern is what happens when tax bills are calculated using an incomplete picture of the market. If some properties are assessed below their true market value because sale information is unavailable, Garate said other properties may end up bearing more of the overall tax burden.
That matters because property taxes are often designed to raise a certain amount of revenue for local governments. If assessments don’t track market value in the way officials intend, the burden can shift quietly.
New Mexico is often cited as a real-life illustration of what disclosure changes can do. The state pursued full nondisclosure until 2004, when it moved toward a partial disclosure law. After that shift. New Mexico saw a roughly 4 percent increase in annual tax revenue—an amount equivalent to $1.09 million. according to a 2025 study.
The same reporting context includes a separate study published in 2004 that concluded New Mexico collected less property taxes than it should have been because high-value homes were not taxed effectively.
Taken together, the implication is stark: if nondisclosure has been keeping some values understated, revenue could be lower than it otherwise would be—and local budgets can’t simply ignore that gap. Eventually, the shortfall tends to show up somewhere, often in the assessments of other properties.
There’s a human consequence to all of this: a property tax bill that feels like it belongs to someone else’s market reality. For homeowners who believe their assessments are wrong, the system can offer a path to challenge. For homeowners who suspect they’ve been overburdened—or those who live next door to an underassessed property—the fairness question doesn’t go away.
The central tension is simple and stubborn. In states where final sale prices stay private. assessors and neighbors may never learn what was paid. while those with access to private transaction details can potentially use that advantage to influence outcomes. The public record. or the lack of it. becomes more than a paperwork issue—it becomes a factor in who carries the tax load.
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