Real estate sale prices are secret in Missouri — even to people who calculate your taxes

Every two years, county assessment departments in Missouri are tasked with calculating hundreds of thousands of property values.

But unlike most states, county assessors in Missouri don’t have a number that could make the process quicker and more accurate — the price that buyers actually paid when they bought the property.

Missouri is one of 12 “nondisclosure” states in the United States. That means real estate sales prices are kept private. The only people who know how much a property sold for are the buyer and the seller — or a real estate agent with access to a multiple listing service database.

There are some workarounds when it comes to single-family homes or condos, but when it comes to big commercial properties, it can be a shot in the dark.

If those assessments are off, taxing jurisdictions like schools, libraries or cities could end up taxing some property owners more than others with the same value.

And if the values don’t meet Missouri’s standards, assessors could place the county’s funding at risk — or in severe cases, throw the local school districts into financial chaos.

That’s why Rep. Emily Weber, a Democrat representing Kansas City in the Missouri General Assembly, proposed a bill that would require anyone who buys property in Missouri to tell the county how much money they paid for it. If not, the state would charge a fine worth 5% of the sales price.

Disclosing those sales prices would build a database that county assessors could use to calibrate their mass-appraisal algorithms and cross-check their assessments.

“Missouri is one of the few states where real estate sales prices are secret to the public and particularly appraisers,” Weber wrote in a statement. “The data is critical to county offices and appraisers who are creating accurate valuations for tax reasons and bank loans.”

The missing numbers

When it comes to residential property, county assessors have relatively reliable data on recent sales that can help with accurate assessment.

Tracy Baldwin, the Clay County assessor, said that the county might knock on someone’s door to verify sales information or use data sources like real estate multiple listing services or CoStar. If they can find out key characteristics like the number of bedrooms and bathrooms, they can get a ballpark figure that tends to be more accurate.

Commercial properties, on the other hand, are a problem.

“There’s no place that you can go to get (commercial) sales prices,” he said. “Some of the data centers, those are a little more difficult to value, or extra-large commercial buildings.”

Without much concrete data, the county can end up undervaluing those properties. And that costs other property owners — such as homeowners — who end up picking up the bill when commercial property owners don’t pay their fair share.

What it means for your property tax bill

If a property assessment is inaccurate, that can affect tax bills for everyone in the school district, city or county.

Say, for example, your house is assessed accurately, but a mall down the street is undervalued (meaning that it’s worth more than the county believes it is).

Taxing jurisdictions — including school districts, public libraries and cities — set the tax rate every year based on the total value of all properties. If the mall is undervalued, everyone’s tax burden will go up to compensate.

That means you would pay more in property taxes to make up for the taxes that the mall owner is not paying because the mall is undervalued.

That’s why accuracy is so important to the assessment process.

“If (assessors) do their job and the values are where they should be, that keeps a handle on tax levies getting either too large or too low,” Baldwin said.

In New Mexico — a state that, like Missouri, does not require property owners to disclose sales prices — a 2004 study found inequities in property tax bills where lower-income families paid disproportionately high property taxes compared to their wealthier neighbors. The study’s authors suggested that this may be connected to inaccurate property assessments due to the lack of real estate sales price disclosure.

What do property assessors think?

Mike Ardis, a spokesman for the International Association of Assessing Officers, said that the organization could not endorse a specific bill.

However, the IAAO’s standards on verification state, “In jurisdictions without laws mandating full disclosure of sales data, assessing officials operate under a significant disadvantage and should pursue legislation to ensure such disclosure.”

Jackson County passed a law in 2003 that requires anyone buying property to submit a “certificate of value” disclosing the price they paid. St. Louis County and the city of St. Louis also require certificates of value.

Marshanna Smith, a spokesperson for Jackson County, said that law makes sure that property assessments are as fair and accurate as possible.

Similarly, Kansas requires property buyers to submit a questionnaire including the sales price to the county appraiser. Those records are destroyed after five years.

The Missouri Realtors organization, however, opposes the bill.

“We believe that sellers and buyers have a right to privacy regarding the purchase of real property,” President Bobbi Howe said in a statement. “We will closely monitor HB 579 should it progress through the legislature this session.”

The bill faces steep odds. Weber introduced similar legislation in 2023 and 2024 but never got a committee hearing.

Baldwin, from Clay County, believes that passing this bill would improve the accuracy of property assessments and in turn help taxpayers in the county.

“I just can’t stress enough how big this bill would be for assessors,” he said.