Independent study confirms claims of systemic overassessments in Detroit are false

• Exhaustive study by International Association of Assessing Officers shows Detroit’s assessment process is fully compliant with state law   

• City Council directed OCFO to select an independent evaluator to review assessment practices, and conduct a sales ratio study 

An independent report by the International Association of Assessing Officers (IAAO) shows once and for all that the City of Detroit’s property assessment practices are fully compliant with state law which shows there is no systemic overassessment taking place at any level of the residential housing market, Chief Assessor Alvin Horhn said today.  

Detroit City Council directed the Office of the Chief Financial Officer to select an independent third party to review assessing practices and conduct a sales ratio study after repeated claims that Detroit was systematically over assessing homes, especially those at the lowest end of the market.  The report shows those claims to be false, as Horhn has maintained year after year.  

“We are very pleased with the results of the independent sales ratio study and analysis by the IAAO because it clearly validates that the City of Detroit has no systemic over assessment issue and is compliant with Michigan law.” Horhn said.  “The study shows Detroit residential property assessments at the level (50% of market value) required by State law, a fact which has been annually confirmed by the Wayne County Equalization Department. This puts the issue to rest once and for all.” 

Specifically, the report states: “The Assessor’s Office for the City of Detroit is compliant with Michigan State law by having an overall mean (average) level of assessment equal to 50.1 with a 95% confidence level ranging between 49.7 and 50.5.” (pg. 44, IAAO Report) 

The report also acknowledges that methods critics have urged the city to use are not allowed under Michigan law. The IAAO report specifically noted: 

“While not directly controlled by the staff in the City’s Assessor’s Office, the sales verification and validation processes in the City, County, and State should include a review and analysis of all market transactions, regardless of the type of deed utilized in the property transfer. As discussed previously in this report, a revision of this practice will require cooperation and concessions made by multiple levels of government, however, finding a solution that allows the city’s assessment staff the ability to fully review and verify the terms of sale for all property transfers throughout its jurisdiction is the best way to serve the entire community of Detroit. Routinely removing a significant portion of the sales transaction file creates a scenario where estimates of market value could be unduly influenced upwards.” 

Horhn pointed out in response that the City of Detroit uses every legal means available to ensure the accuracy of its assessments.  

“We go to great lengths to make sure our valuations reflect the true value of homes in each neighborhood, by taking into account all forms of sales, including cash sales and land contracts – not just traditional market sales,” said Horhn. “We also consider the unique economic conditions in each of the city’s more than 200 individual neighborhoods to make sure we are being as precise in our assessments as all available data allow.”  

Over the past two years, the Coalition for Property Tax Justice has appealed hundreds of assessments, claiming they were inflated and resulted in homeowners being over taxed. Those appeals were all reviewed by the Board of Review, which is appointed by Detroit City Council and independent of the Assessor’s office. The results show overwhelmingly that nearly 98% percent of the property assessments were accurate and resulted in no change in taxable value.  

2024 Coalition appeals 544 

Denied by Board of Review 414  

Approved for value change 130 

Taxable value reduced 11 (2% of total) 

2025 Coalition appeals 251 

Denied by Board of Review 166  

Approved for value change 81 

Taxable value reduced 10 (4% of total) 

 Lastly, it should be noted that in Michigan the assessed value does not determine the amount paid in property taxes for the homeowner who remains in their home. Since 1994 Michigan law imposes property taxes on the taxable value of property which, unless the property has been sold, could not increase in any year by more than the rate of inflation or 5%, whichever is less.  As illustrated in the chart below for residential properties, the taxable values are considerably lower than the assessed values.