Mandatory disclosure of real property sales prices through real property Certificates of Value (COV) ensures uniformity for property taxes in MO (STC 2020). The sales price information from COV represents market conditions, allowing the assessor to evaluate properties at their actual monetary value as required by law. Assessors use ratio studies to examine the relationship between appraised or assessed values and market values, using indicators like sales prices (sales ratio study) or expert appraisals (appraisal ratio study) (IAAO 2020).
State Tax Commission (STC) considers sales ratio studies as the most effective method for residential property assessment, but the sales ratio study is limited by incomplete sales price records in MO (STC 2019). Some of the purposes of ratio studies are to monitor the accuracy of assessments, allocate intergovernmental funds, including the allocation of state funding to local school districts and to estimate the market value of properties taxed in a jurisdiction (STC 2019).
Some states in the U.S. publicly disclose real estate sale prices (disclosure states) while others do not (nondisclosure states) (Table 1; Bollum 2021). However, some of the nondisclosure states provide sales price data exclusively to assessors but not to the public, making them partial nondisclosure states (Table 1).
MO is a nondisclosure state for real estate sale prices. In most MO jurisdictions sale price disclosure is voluntary however St. Charles County, St. Louis County, Jackson County, and St. Louis City have ordinances mandating sales price disclosure through real property Certificates of Value (COV) (STC 2020). In MO, data from COV accounts for nearly 50% of locally assessed property sales. However, in jurisdiction with voluntary disclosure, only 15-25% of sales prices are received, resulting in insufficient data to accurately reflect market trends (STC 2020).
There is limited data on the impact of sales price nondisclosure laws on real estate prices and the real estate market. Decline in market transparency leads to challenges in property valuation and informed decision-making for buyers, sellers, and difficulty in calculating property taxes (Berrens & McKee 2004). One study found that nondisclosure laws can reduce property tax revenue (Berrens & McKee 2004). Another study showed that after transitioning from a nondisclosure to partial nondisclosure law in 2004, NM experienced 4% increase in annual tax revenue, leading to approximately $1.09 million increase (Bollum 2021). While sales price disclosure aids assessors in improving property valuations for taxation, more data on nondisclosure laws could provide further insight into their overall impact (Bollum 2021).
Table 1. Different categories of real estate sales price disclosure in the U.S.
| Category | Definition | Availability of Sales Data | Examples of States | Source |
| Disclosure states | Sale prices are publicly available | Public and assessors have access | CO, and NV | (Bollum 2021; CRS § 39-13-101; NRS § 375.060). |
| Nondisclosure states | Sale prices are not required to be disclosed | Not available to the public or assessors. | ID and UT | (Berrens & McKee 2004; Bollum 2021). |
| Partial nondisclosure states | Sale prices are recorded but not public. | Assessors have access, but not the public. | MT, NM, KS, and WY | (MCA §15-7-308; NMS § 7-38-12.1; KSR § 79-1437d; WS § 34-1-142e).
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Berrens RP and McKee M (2004) What Price Nondisclosure? The Effects of Nondisclosure of Real Estate Sales Prices. Social Science Quarterly 85(2): 509–520. https://www.jstor.org/stable/42955956
Bollum T (2021) Public revenue leakage from real estate non-disclosure laws. Montana: Montana State University. https://scholarworks.montana.edu/handle/1/16238
Certificate of value (n.d.) St. Louis City, MO. https://www.stlouis-mo.gov/government/departments/assessor/documents/upload/COV.pdf
Colorado Revised Statutes § 39-13-101 (2024) Legislative declaration. https://leg.colorado.gov/sites/default/files/images/olls/crs2024-title-39.pdf
International Association of Assessing Officers (IAAO) (2020) Standard on verification and adjustment of sales https://www.iaao.org/wp content/uploads/Standard_on_Verification_Adjustment_of_Sales.pdf
Kansas Office of Revisor of Statutes § 79-1437d. Same; devised by director of property valuation; approval by legislature; information to be contained therein. https://www.ksrevisor.org/statutes/chapters/ch79/079_014_0037d.html
Montana Code Annotated § 15-7-308 (2023) Disclosure of information restricted -- exceptions 15-7-308. Disclosure of information restricted -- exceptions, MCA
Nevada Revised Statutes § 375.060 (2009) Declaration of value of property. https://www.leg.state.nv.us/NRS/NRS-375.html#NRS375Sec060
New Mexico Statutes § 7-38-12.1. Property transfers--affidavit to be filed with assessor. https://www.nmlegis.gov/sessions/99%20Regular/FinalVersions/HB0858.html
Real Property Certificate of value (n.d.) Jackson County, MO. https://www.jacksongov.org/files/sharedassets/public/v/1/services/certificate-of-value-cov-pdf.pdf
Real Property Certificate of value (n.d.) St. Charles County, MO https://www.sccmo.org/DocumentCenter/View/80/Certificate-of-Value-Form-PDF
Real Property Certificate of value (n.d.) St. Louis County. https://stlouiscountymo.gov/st-louis-county-government/county-assessor/assessor-forms/certificate-of-value/
Wyoming Statutes § 34-1-142(e) Instrument transferring title to real property; procedure; exceptions; confidentiality. https://www.wyoleg.gov/statutes/compress/title34.pdf
State Tax Commission Annual Report (STC) (2020) Recommendations to The Missouri Legislature Section 138.380(4). https://stc.mo.gov/wp-content/uploads/sites/5/2021/02/2020-Recommendations.pdf
State Tax Commission of Missouri Assessor Manual (STC)(2019) Ratio Study. https://stc.mo.gov/county-ratios/wp-content/uploads/sites/5/2016/11/CHAPTER4-REV-11-16-2016.pdf
