How do you appeal the property tax assessment on an apartment building?
File a protest or appeal by your county's deadline, then show what the building actually earns: a rent roll, a trailing 12 month income and expense statement, and a value worked out from that income. In Texas the usual deadline is May 15 or 30 days after the appraisal notice is mailed, whichever is later; in Cook County it is typically 30 days after your reassessment notice.
Why apartment owners have an edge
Assessors value apartment buildings partly by what similar buildings earn. If yours earns less, because of higher vacancy, older systems, or expenses the market data misses, your own books are the evidence. A homeowner argues with photos and nearby sales; an apartment owner can argue with numbers the assessor already uses.
Deadlines: two examples
| Place | Deadline | Who hears it | What to know |
|---|---|---|---|
| Texas | May 15 or 30 days after the appraisal district mails its notice, whichever is later | The appraisal review board (ARB) | The 30 days run from mailing, not delivery. You can ask for the evidence the district will use, and must get notice of that right at least 14 days before the hearing. |
| Cook County, Illinois | Typically 30 days after your reassessment notice; the last filing date is printed on it | The Assessor first | Townships open on a calendar. If you miss it, you can appeal the following year. Supporting documents must be filed with the appeal. |
Sources: the Texas Comptroller and the Cook County Assessor. Every other state and county has its own calendar, so find yours on the notice or the assessor's site.
The evidence packet
The Texas Comptroller is blunt: you cannot go to the hearing and just say the appraisal district is wrong. Bring proof. Useful items include photos, repair estimates and sales documents. For apartment buildings of 7 or more units, the Cook County Assessor files appeals online through the commercial form and lists a rent roll form and vacancy affidavits among its documents (Cook County, apartments with 7+ units).
- A current rent roll: every unit, its rent, and whether it is occupied.
- The last 12 months of income and expenses, by category, from your books.
- Vacancy for the year, with dates units sat empty.
- Bids or invoices for major repairs the building needs, with photos.
- The assessor's own data, if you can get it, so you argue from their cap rate and rents.
Leave loan payments and depreciation out of the expenses. Assessors value the property, not your financing or your tax return.
A worked income approach
Example a made-up 16 unit building is assessed at a market value of $2,400,000. Its rents total 16 x $1,250 x 12 = $240,000 a year. Actual vacancy was 8%, or $19,200, and laundry brought in $6,000, so effective income is $240,000 - $19,200 + $6,000 = $226,800. Operating expenses, not counting loan payments or depreciation, were $98,000, so net operating income is $128,800. At a 6.0% cap rate taken from the district's own evidence, value is $128,800 / 0.06 = $2,146,667, which is $253,333 below the assessment.
Where property taxes go in that math depends on the place. Some assessors leave taxes out of expenses and add a tax rate to the cap rate instead. Ask, or follow the method in the district's evidence, and do not count taxes twice.
There is no promise the board agrees, and a lower value only lowers your bill if the tax rate stays the same. The work is mostly pulling numbers you already have.
A simple timeline
- When the notice arrives: write the filing deadline on your calendar and compare the value with your own estimate.
- Within a week: file the protest or appeal, even if the packet is not ready, if your county allows evidence later. Cook County does not: file it together.
- Two weeks: request the district's evidence where you can, and build your packet.
- Before the hearing: send the packet as required and prepare a one-page summary of your number.
- After the decision: record any change in your books and note next year's deadline.
Pulling the numbers from DoorKeeping
Because DoorKeeping keeps one set of books per property, you can ask your AI app for the building's profit and loss or its net operating income for the last 12 months, and see each expense by category. The bank feed shows which units paid each month, which backs up the vacancy you claim. DoorKeeping costs $2 per unit per month and does not file appeals or give tax advice.
Sources
- Texas Comptroller, Property tax protests and appeals, read Oct 30, 2026
- Cook County Assessor's Office, Appeals, read Oct 30, 2026
- Cook County Assessor's Office, Apartment with 7+ units, read Oct 30, 2026
Questions
- When is the property tax protest deadline in Texas?
- In most cases May 15 or 30 days after the appraisal district mails its notice, whichever is later, according to the Texas Comptroller.
- What do I need to appeal an apartment building assessment?
- A rent roll, a trailing 12 month income and expense statement, vacancy records, and evidence of needed repairs. Cook County lists a rent roll form and vacancy affidavits for apartments of 7 or more units.
- Should mortgage payments count as expenses in a tax appeal?
- No. Assessors value the property, so leave out loan payments and depreciation and use operating expenses only.