Detroit apartment buildings are assessed by the City of Detroit’s own Office of the Assessor, at 50% of market value, and taxed on a “taxable value” that Michigan’s Proposal A caps until the property sells. For a building with five or more units, three things matter most: its commercial classification, the cap and what happens when it comes off, and Detroit’s unusually high millage.
Who Sets the Value of a Detroit Apartment Building
Detroit runs its own assessing operation, the Office of the Assessor, inside the city’s Office of the Chief Financial Officer. Every property is valued as of December 31 for the following tax year. Michigan law sets the state equalized value (SEV) at 50% of true cash value, so a building the assessor believes is worth $2 million carries an SEV of roughly $1 million.
Classification is the first thing to check on an assessment notice. Under MCL 211.34c, apartment buildings with more than four units are classified as commercial real property, while duplexes, triplexes and fourplexes fall under residential. That distinction drives appraisal method (income-producing buildings are often reviewed against rents and expenses) and, as covered below, appeal deadlines.
Taxable Value, the Proposal A Cap and the Uncapping Year
The bill is not calculated on SEV. It is calculated on taxable value, which under Proposal A can rise each year by no more than the lesser of 5% or the inflation rate multiplier. For 2026 that multiplier is 1.027, or 2.7%, as published in local assessing guides such as the City of Portage’s Understanding Proposal A 2026.
Long-held buildings can therefore carry a taxable value far below half of today’s market value. That gap closes all at once after a transfer of ownership: in the year following a sale, taxable value “uncaps” and resets to that year’s SEV. A few practical points follow:
- A buyer’s property tax line can jump in the first full year of ownership, so the seller’s current bill rarely represents what the next owner will pay.
- The buyer must file a Property Transfer Affidavit within 45 days of the transfer; late filing carries a penalty of $5 per day, up to $200.
- Because the uncapped value is based on SEV, not the purchase price, a high sale price does not automatically become the new taxable value, but it is evidence the assessor will see.
Why Detroit’s Millage Rate Changes the Math
Detroit’s millage rates are among the highest in Michigan, a point made in 2026 by both University of Michigan Ford School researchers and local reporting on Mayor Mary Sheffield’s push for deeper tax relief, which would require approval from the state Legislature. Apartment buildings sit on the higher end of the city’s rate structure because they cannot claim the principal residence exemption, which the Michigan Department of Treasury describes as exempting an owner-occupied home from local school operating millage of up to 18 mills.
For investors, the practical effect is that property tax is often one of the largest operating expenses on a Detroit apartment budget. Small differences in assessed value translate into meaningful differences in net operating income, and in what the building is worth to the next buyer.
Appeal Windows Detroit Owners Should Calendar
Detroit offers several chances to contest a value, according to the city’s property assessment appeal page:
- Assessor Review, February 1–22. An informal first look by the assessor’s office after notices go out.
- March Board of Review. Runs from the Tuesday after the first Monday in March through the first Monday in April.
- Michigan Tax Tribunal. The Tribunal’s deadline for commercial real property, which includes buildings with more than four units, is May 31. Residential property, including two- to four-unit buildings, follows the July 31 deadline.
- July and December Boards of Review. Later sessions with a narrower scope; check the city’s page to see what each can hear before relying on them.
Appeals on income-producing buildings tend to turn on documentation: a current rent roll, trailing 12-month operating statements, recent capital work and evidence of physical problems such as fire damage or vacant units that are not rent-ready.
What This Means for Owners
If you are holding, the priority is making sure the classification and the value on your notice reflect the building’s actual income and condition, and appealing on time when they do not. If you are planning an exit, model the buyer’s tax bill on an uncapped value, because any buyer’s underwriter will. Running the figures through our NOI calculator with both the current and an uncapped tax line shows how much of the price gap is really a tax question.
For local context on demand and pricing, see our Detroit market page and our overview of apartment markets across Michigan.
