When the Assessor and your client’s appraiser both use the income approach, why do the values sit so far apart? In an income approach tax appeal, the answer usually sits in two inputs, net operating income and the cap rate. Both are getting a harder look in 2026, because Cook County changed how real estate taxes enter the cap rate.
- How the Assessor builds a commercial value, and what changed for 2026
- Which income records the Assessor and the Board of Review expect in a file
- How a lender can test a reassessed value against a borrower’s real income
How the Assessor Builds Value in an Income Approach Tax Appeal
The Assessor’s Office values most commercial property with the income approach, applied through mass appraisal. Its published method starts with potential gross income at estimated market rents. Then it takes out vacancy and collection loss and subtracts typical operating expenses. The resulting net operating income is divided by a market cap rate. If you want the logic behind each step, our guide to how appraisers use the income approach walks through it.
The inputs reflect market data and past appeals on similar properties, so they describe a typical building, not your client’s. That is why the model can miss a below-market lease or a tenant who stopped paying. The Assessor’s own commercial brochure addresses this. It says a below-market lease may support a reduction if detailed income and expense records back it up.
After the value is set, the county ordinance level applies. Office, industrial, and retail buildings typically assess at 25% of market value, while apartment buildings assess at 10%.
Cook County reassesses in thirds, and the south and west suburbs are in the 2026 cycle. Township windows open on a rolling schedule, so the Assessor’s calendar is the place to confirm a date. Our earlier piece on the 2026 south suburbs reassessment covers when a second opinion makes sense.
The 2026 Loaded Cap Rate Changes the Arithmetic
Starting in 2026, the Assessor applies a loaded cap rate to all commercial properties under its cap rate policy. Real estate taxes no longer come out as a line item in operating expenses. Instead, a tax load gets added to the market cap rate.
The load is the level of assessment times the equalization factor times the tax rate. The policy’s own example multiplies 25% by a 3.0355 equalization factor and an 8.970% tax rate. That gives 6.81%.
The south townships carry a wrinkle. The Assessor estimated their 2026 tax rates by mirroring the 2023 actual rates, and it uses the 2023 equalization factor. Your client’s current bill may tell a different story, so the load is worth comparing with it.
Consider a hypothetical building with $500,000 of net operating income before real estate taxes. Assume a 7.00% market cap rate and a 6.81% tax load. The loaded rate is 13.81%, so the indicated value is about $3,620,565. At the 25% level, the assessed value would be about $905,141.
Now check it from the other direction. Taxes at that value run about $246,560, which leaves about $253,440 of income. Capitalized at 7.00%, that returns roughly $3.62 million, the same answer. The two methods agree because the taxes sit in one place only.
Mixing them breaks the math. Suppose a report deducts $200,000 of actual taxes and also applies the loaded rate. Value falls to about $2,172,339, roughly 40% lower, because the taxes were counted twice. Rate moves matter too. A 50 basis point rise in the market cap rate lowers value to about $3,494,060 in the same example. That is a drop of about 3.5%. These figures are illustrative and are not Assessor data.
So ask one question of every income analysis in your file. Do the taxes sit in the NOI or in the rate? The answer has to match on both sides of the formula, and the report should say which basis it used.
Where Net Operating Income Gets Tested
Appeals on income-producing property now include Real Property Income and Expense filing. The online filing page warns that missing or incomplete information may produce a no change result. The Assessor’s brochure lists three years of income and expense records. It also asks for rent rolls, leases, an appraisal if available, and recent sales documents.
At the Board of Review, one commissioner’s published guidance for leased property covers the rent roll and leases. It also lists three years of IRS Schedule E, photographs, and a vacancy affidavit. Each township is open at the Board for a 30-day window. For the appraisal side, see what a tax appeal appraisal must contain.
Clean records come first. Strip out depreciation, debt costs, capital expenses, and payments to owners. The Assessor leaves those out of operating expenses too. Our overview of net operating income in commercial real estate shows what belongs above the line.
The harder part is reconciling the owner’s actual income with market income. Contract rents above or below market change the picture. A Board of Review summary of the 2022 appeal cycle says the Board checks whether leases sit at market rates. Your appraiser supports that comparison with leases and market rent evidence. How it fits a legal theory stays with counsel.
Vacancy Claims Follow a Published Formula
The Assessor’s valuation already carries a market vacancy factor, so a vacancy claim has to go beyond it. Under the vacancy policy, a reduction applies when conditions outside the owner’s control keep a building from its intended use. The policy recognizes market, renovation, and casualty vacancy, and it limits any reduction to 24 months per event.
For market-related vacancy, the formula takes half of the weighted annual vacancy and subtracts the vacancy already in the valuation. Take 60% weighted vacancy with 10% already in the valuation. That is 30% less 10%, an additional 20% reduction to the building’s assessed value.
The documents matter as much as the math. The policy asks for a month-by-month vacancy affidavit, a twelve-month rent roll, proof the space was marketed, and utility bills. If the file can’t show those, the number won’t carry.
What Lenders Should Do With a Reassessed Value
Bankers see this from the other side. A reassessment can move the tax line in a borrower’s NOI long before any appeal is decided. The Assessor’s value is not a collateral value. It is a mass appraisal built for tax purposes.
So when a notice arrives, ask the borrower for the Assessor’s methodology report for the township. It shows how each PIN was reassessed. Set the income, vacancy, expense, and cap rate inputs next to the borrower’s rent roll and your own appraisal. If the borrower has filed an appeal, ask to see the filing and the income evidence behind it. Treat any hoped-for reduction as unrealized until a decision issues.
Put the Income Evidence and the Cap Rate on the Same Basis
Start early. Gather three years of income and expense statements, the current rent roll, and the leases. Ask your appraiser to state whether taxes sit in the NOI or in the cap rate. Have the market rate and the vacancy supported with evidence you can hand to the Board. Then confirm the township window, because they open on different dates and close on schedule.
PahRoo establishes value from the evidence. Whether a given fact pattern meets a legal standard stays with you and the Board.
Is Your Cap Rate Loaded or Unloaded?
Send us the rent roll and the Assessor’s notice. We will build the income case on one consistent basis. Your NOI and cap rate then hold together at the Board.
Frequently Asked Questions
How is commercial property valued for a Cook County tax appeal?
The Assessor values most commercial property with the income approach, applied through mass appraisal. It uses market rents, vacancy, expenses, and a market cap rate. In an appeal, an owner can present actual income records and an appraisal to support a different value. The Assessor defines fair market value as what a property could sell for between willing parties.
What income evidence does the Board of Review want?
Board of Review guidance for leased commercial property covers the rent roll and leases. It also lists three years of IRS Schedule E, photographs, and a vacancy affidavit where it applies. Owner-occupied property needs an appraisal completed in the past three years. Check the current filing rules before you submit, because requirements can change.
Do commercial tax appeals need an appraisal?
It depends on the property and the filing. Board of Review guidance asks for an appraisal on owner-occupied property, while leased property leans on income records. Illinois Property Tax Appeal Board rules list an appraisal as one form of proof of market value. A recent sale, comparable sales, and construction costs are others. Your attorney decides which evidence fits the case.
What cap rate does the Assessor use?
There is no single rate. The Assessor derives a market cap rate from market data, third-party sources, past appeals, and comparable sales. Starting in 2026 it adds a tax load to that rate. The loaded rate therefore runs higher than the market rate alone. The methodology report for your township shows what was applied to each property.
How does vacancy affect a commercial assessment?
The Assessor’s valuation already includes a market vacancy factor. A commercial vacancy reduction applies when conditions outside the owner’s control keep a building from its intended use. Any reduction is limited to 24 months per event. The owner documents the claim with a vacancy affidavit, a rent roll, proof of marketing, and utility bills.
Income Approach Appraisals for Cook County Appeal Files
PahRoo Appraisal and Consultancy prepares income approach appraisals from our Lincolnwood office. We work with attorneys, lenders, and property owners across Cook County. If you are still deciding whether to appeal, start with our overview of Cook County tax appeals. You can also read when a commercial real estate appraisal makes sense.