Cook County property tax: rates, bills, appeals, and deadlines

Last updated 2026-07-09

What makes Cook County property taxes different from the rest of Illinois?

Cook County runs one of the most tangled property tax systems in the country. High rates are part of it. The bigger problem is that the assessment cycle, the appeal layers, the exemptions, and the billing calendar all feed into each other in ways that trip up even homeowners who've owned here for decades.

The county assesses on a triennial cycle. Each of the 38 townships gets reassessed once every three years on a rotating schedule ^[1]. Your township's reassessment year sets when you'll get a Notice of Proposed Assessment and when your appeal window opens. Miss that window and you're locked out for the cycle.

The Illinois Property Tax Code (35 ILCS 200) governs the whole thing ^[2]. The Cook County Assessor sets the first value. Disagree, and you appeal to the Assessor, then to the Cook County Board of Review, then to the Illinois Property Tax Appeal Board or circuit court. Three separate bites at the apple, each with its own deadline.

The effective tax rate in Cook County averages about 2.08% of market value against a national median near 1.1% ^[3]. On a $350,000 home, that gap runs over $3,000 a year. Getting your assessment right is not a minor clerical task.

How does Cook County calculate what your property is worth?

The Assessor estimates your fair market value, then applies an assessment level. Residential property (Class 2) is assessed at 10% of estimated market value ^[1]. A home the Assessor values at $400,000 carries an assessed value of $40,000 on paper.

That $40,000 gets multiplied by the state equalization factor (the "multiplier"), which the Illinois Department of Revenue sets each year to line Cook County's total assessed value up with the statewide standard. For 2023 taxes (paid in 2024), the Cook County factor was 2.9109 ^[4]. That turns your $40,000 into an equalized assessed value (EAV) of about $116,436.

Your bill then works out to EAV, minus exemptions, times the composite tax rate for your tax code area. Each area is different because it reflects the school districts, park districts, library districts, and municipalities stacked over your parcel. Cook County has more than 1,900 tax code areas ^[1].

This is why two neighbors with identical homes can owe slightly different amounts. The Assessor's market value estimate is the starting point, not the finish line.

What are Cook County property tax rates by municipality?

There is no single Cook County tax rate. The tax code area system produces thousands of effective rates depending on where your parcel sits. The table below shows approximate 2023 composite rates (the most recent levy year with complete data) for selected municipalities ^[3].

Municipality	Approx. Composite Rate (2023)
Chicago (avg.)	1.73% of market value
Evanston	2.84%
Oak Park	3.64%
Cicero	3.91%
Harvey	6.50%+
Schaumburg	2.20%
Naperville (Cook portion)	2.00%

Rates here are shown as a percentage of estimated market value (not EAV) so homeowners can compare them without doing multiplier math. Harvey has topped 6% in recent years mostly because property values there are low relative to what the taxing districts levy ^[3].

You can pull the exact rate for any parcel through the Cook County Treasurer's payment portal or the Assessor's Property Detail page ^[5]. You need your 14-digit Property Index Number (PIN). It's on your tax bill and your deed.

When are Cook County property taxes due in 2025 and 2026?

Cook County bills in two installments.

The first installment for tax year 2024 (billed in 2025) was due March 3, 2025 ^[5]. That installment is always exactly 55% of the prior year's total bill, no matter what happens to your assessment or exemptions. Think of it as a prepayment.

The second installment date rides on when the Assessor and Board of Review finish and when bills go out. It has usually landed in late July or August, but delays are routine. The 2023 second installment got pushed to December 1 because assessment work ran late in many townships ^[5]. For tax year 2024's second installment, the Treasurer targeted August 1, 2025. Verify it at the Treasurer's office, because that date moves.

For tax year 2025 (billed in 2026), the first installment will be due March 2, 2026. The 2026 second installment date isn't set as of this writing.

Late payments run interest at 1.5% per month, or 18% a year, under Illinois law ^[2]. No grace period. If the due date falls on a weekend or holiday, payment is due the next business day.

You can pay online, by mail, at Chase Bank locations in Illinois, or at the Treasurer's downtown office. The payment portal is on the Cook County Treasurer's website ^[5].

What are the Cook County property tax appeal deadlines for 2025 and 2026?

This is the section most people come for, and it's where most mistakes happen. The Cook County property tax appeal deadline is not one county-wide date. It changes by township and by which office you're appealing to.

Here's the mechanics. Each year the Assessor opens an appeal window for every township in the reassessment cycle. The window usually runs 30 days from the date the Assessor publishes that township's assessment roll. Then the Board of Review opens its own window after the Assessor closes. Two real deadlines, not one.

Cook County Assessor appeal windows (2025, selected townships) ^[1]:

Township	2025 Assessor Appeal Open	Approx. Deadline
Bloom	February 2025	~March 2025
Bremen	February 2025	~March 2025
Calumet	February 2025	~March 2025
Chicago (South reassessment 2025)	Watch Assessor site	30 days after notice
Orland	Watch Assessor site	30 days after notice

The 2025 reassessment year covers the south and southwest suburbs. The 2026 reassessment covers the north suburbs. The city of Chicago reassesses on its own triennial cycle ^[1].

For the 2025 and 2026 appeal deadlines, the one reliable source is the Cook County Assessor's township appeal schedule, updated each year as the Assessor publishes each township's roll ^[1]. Don't trust any third-party calendar, including this one, as the controlling date. Deadlines shift when roll publication slips.

The Board of Review runs a separate calendar. Its window for each township opens after the Assessor closes and usually runs 30 to 45 days. The Board posts its schedule on the Cook County Board of Review website ^[6].

Missing the Assessor deadline doesn't shut every door. You can still go to the Board of Review. Missing the Board of Review deadline is the one that hurts.

Can you appeal property taxes after the deadline?

For the current assessment year, no, and Illinois courts have backed that up over and over. Once the Board of Review's window closes for your township, you can't file a complaint for that tax year ^[2].

The exceptions are narrow. If you got a Certified Notice of Assessment and can prove you never received it through no fault of your own, you may have a procedural argument, but it's rare and it needs documentation. The circuit court can hear appeals under the Administrative Review Law, but only after you've exhausted the administrative remedies, meaning you filed at both the Assessor and Board of Review levels first ^[2].

The Illinois Property Tax Appeal Board (PTAB) is another route, again only for appeals properly filed at the Board of Review first. PTAB hearings can run 12 to 36 months and make more sense for commercial owners with real dollars on the line ^[8].

Missed the deadline? Calendar every deadline for next year right now, confirm all your exemptions are applied (those don't need an appeal), and file the moment the next window opens. For the official 2026 schedule, check the Assessor's site in late 2025 or early 2026 as the north suburb reassessment rolls out ^[1].

Exemptions are the one thing that can cut your bill without an open appeal window. They lower your EAV directly. Verify yours before you do anything else.

What exemptions can lower your Cook County property tax bill?

Cook County offers more exemptions than most Illinois counties, and plenty of homeowners leave money on the table by skipping some. The main ones ^[1][7]:

Homeowner Exemption: Cuts EAV by $10,000. Applies to any home you occupy as your primary residence. Automatic after your first qualifying year, but check that it's on your bill every year.

Senior Citizen Homestead Exemption: Cuts EAV by $8,000 for homeowners 65 and older. Apply through the Assessor.

Senior Freeze (Senior Citizens Assessment Freeze Homestead Exemption): Freezes your EAV at the level from the year you first qualify, as long as household income stays at $65,000 or less under the current threshold ^[7]. This one earns its keep in rising markets because it locks your taxable base.

Veterans with Disabilities Exemption: Ranges from $2,500 to a full exemption depending on the service-connected disability rating ^[7].

Returning Veterans Exemption: $5,000 EAV reduction for veterans returning from active duty.

Home Improvement Exemption: Lets up to $75,000 in added value from improvements stay out of your assessment for up to four years ^[1].

Natural Disaster Homestead Exemption: Applies when a natural disaster causes substantial damage.

Most exemption applications go through the Assessor's office. Deadlines vary by type but mostly track the assessment year calendar. Check which exemptions are already on your parcel through the Assessor's Property Detail page ^[1].

How do you do a Cook County property tax search?

Two portals, two jobs.

The Cook County Assessor's Property Detail page is where you look up your assessed value, estimated market value, exemptions applied, and the comparable sales the Assessor used ^[1]. Search by PIN, address, or owner name. This is the site you need before you file any appeal.

The Cook County Treasurer's payment portal is where you look up actual tax bills, payment history, and whether your taxes are current ^[5]. You can look up any property by PIN, which helps when you're pulling comparables.

Start at the Assessor's site for an appeal. Read your property's characteristics: square footage, bedrooms, construction quality, land size. Errors here are common and sometimes big. A finished basement coded as unfinished, or a phantom extra bathroom, can inflate your assessed value 10% or more.

Then run the Assessor's comparable sales search to see what the model leaned on. Wrong comps are your evidence. If your characteristics are correct and the comps are reasonable, the case gets harder, though not hopeless, especially when nearby homes like yours carry lower assessments.

How do you file a Cook County property tax appeal yourself?

Step one: find your Notice of Proposed Assessment. It arrives by mail during your township's reassessment year. No notice? Look up your current assessed value on the Assessor's site. The appeal window opens when the Assessor publishes the township roll, not when your notice lands in your mailbox.

Step two: gather evidence. The two strongest kinds are (a) a recent appraisal or arm's-length sale price showing market value below the Assessor's number, and (b) uniformity evidence showing comparable homes are assessed lower than yours ^[6]. The Board of Review's own numbers show evidence-backed appeals win at meaningfully higher rates than bare assertions.

Step three: file at the Assessor first if that window is still open, then at the Board of Review. Both take online filings. The Board of Review's residential appeal is filed through its online portal ^[6].

Step four: submit your presentation. Most residential Board of Review appeals are decided on the written record, so your submission is your hearing. Include your evidence as clearly labeled exhibits.

Step five: wait. Board of Review decisions usually land 3 to 9 months after filing. Win, and the reduction flows through to a corrected second installment bill or a credit against future bills.

Want a structured way to gather comps, organize evidence, and write the argument? The TaxFightBack DIY appeal kit walks through each step and lets you keep 100% of the savings, no contingency fee. That's worth saying once, because Cook County contingency firms usually take 25% to 40% of your first year's savings. On a $2,000 reduction, that's $500 to $800 you'd hand over for work you can do yourself.

For how other large counties run this, see our guides on Los Angeles County property tax, Fairfax County property tax, and Cuyahoga County property tax.

What does the Board of Review actually look at, and what evidence wins?

The Board of Review weighs two independent grounds for a cut: overvaluation and lack of uniformity ^[6].

Overvaluation means the Assessor's estimated market value tops what the property would actually sell for. Evidence: a fee appraisal, a recent arm's-length sale, or a broker's comparative market analysis. The Board accepts appraisals done within 12 months of the assessment date.

Lack of uniformity means comparable homes in your area are assessed at a lower share of market value than yours. This is often the stronger play in Cook County, because the mass-appraisal model spits out inconsistent results across similar houses. Evidence: three to five comparable properties (ideally within a half-mile, similar size and age) carrying lower assessments, pulled from the Assessor's own data. The Board's published Rule 11 spells out what counts as a valid comparable ^[6].

What flops: general gripes about high taxes, comparisons to your purchase price, vague claims that the neighborhood is sliding. The Board needs specific, property-level evidence tied to the assessment in question.

The Board of Review's 2024 annual report shows roughly 275,000 appeals filed, with about 60% of residential appeals getting some reduction ^[6]. Real number, but it counts tiny reductions too. Meaningful cuts of 10% or more come from appeals with actual comparables or an appraisal, not from empty ones.

What happens to your appeal if taxes are already paid or bills are delayed?

Paying your bill does not touch your appeal rights. You can pay in full and still have a pending appeal at the Board of Review or PTAB. Win after paying, and the reduction comes back as a credit on a future bill or, in some cases, a refund.

Bill delays are baked into the Cook County system. The second installment has run late in several recent years, including 2021 and 2023, pushing due dates to November or December instead of the usual August ^[5]. When that happens, the Treasurer's office typically announces extended due dates and suspends penalty accrual for the affected period. Watch the Treasurer's website for those announcements.

Buying or selling in Cook County? A delayed second installment creates title headaches, because the liability may not be known at closing. Buyers should negotiate a tax proration based on a reasonable estimate and write a post-closing reproration clause into the contract. That's standard practice in Cook County deals.

Other big jurisdictions handle timing very differently. San Diego, for one, holds a rigid December 10 / April 10 schedule with no history of county-wide delays. See our San Diego property tax guide for the contrast.

What if you own commercial property in Cook County?

Commercial property (Class 5) is assessed at 25% of estimated market value against 10% for residential Class 2 ^[1]. That's no small technicality. A property carrying $1 million in commercial EAV would sit at $400,000 EAV if it were residential. Classification errors on mixed-use or small commercial parcels get expensive fast.

Commercial appeals climb the same Assessor and Board of Review ladder as residential, but the stakes justify professional appraisals, income-approach valuations for income-producing property, and sometimes PTAB hearings. The Illinois Property Tax Appeal Board (35 ILCS 200/16-160) lets commercial owners skip the circuit court route and get a de novo hearing on value ^[8].

Bigger portfolios also deal with the Cook County classification ordinance, which sets separate rates for office, retail, industrial, and apartment properties. Class 6B for industrial rehabilitation, Class 7 for commercial development, and Class 8 for enterprise-zone properties can cut assessments sharply for eligible projects ^[1].

If your commercial assessment looks off, start with a property search at the Assessor's site to check your classification and characteristics. Misclassified property, especially small mixed-use buildings, shows up often.

For another large urban commercial comparison, see our DC property tax guide.

What's the full Cook County property tax appeal process from notice to resolution?

Here's the timeline most residential homeowners actually live through.

Year 0, spring to summer: Notice of Proposed Assessment arrives. This triggers your Assessor appeal window. You get 30 days from the date the township roll is published (check the Assessor's site for the exact date, not the date your notice showed up). File the Assessor appeal online ^[1].

Year 0, fall to winter: Assessor issues a decision. A reduction is good news. If you get nothing, or less than you wanted, you move to the Board of Review. Its window for your township usually opens October through December of the same year. Check the Board's site for the official date ^[6].

Year 1, spring to fall: Board of Review hearing and decision. Most residential cases are decided on the written record within 3 to 9 months. A decision letter arrives by mail and shows in your online account.

Year 1 to 2: Still unhappy? File at PTAB or circuit court. PTAB filings must land within 90 days of the Board of Review decision ^[8]. Circuit court appeals under the Administrative Review Law follow similar timing. Both make sense mainly for cases with $5,000 or more in annual tax at stake.

Year 1 to 2: Your bill reflects the change. A Board of Review reduction hits the second installment bill if the decision comes before bills are calculated, or shows as a credit on the following year's bill if it comes after.

Total time from Notice of Proposed Assessment to a resolved reduction on your bill: 12 to 24 months in most cases. It's a long cycle. That's exactly why you file every time your township is in its reassessment year. Wait for the next cycle and you eat three years of overpayment.

The TaxFightBack DIY appeal kit has template forms and a comparable worksheet built for Cook County's Board of Review requirements. It's made for homeowners who don't want to split their savings with a contingency firm.

Frequently asked questions

When are Cook County property taxes due in 2025?

The first installment for tax year 2024 was due March 3, 2025 and equals 55% of the prior year's total bill. The second installment is targeted for August 1, 2025, but Cook County second installments have run late in recent years. Confirm the current date at the Cook County Treasurer's office before assuming August 1 holds.

What is the Cook County property tax appeal deadline for 2025?

There is no single county-wide date. Each township has its own Assessor appeal window, which opens when the Assessor publishes that township's roll and runs 30 days. The Board of Review then opens a separate window. For 2025, south and southwest suburb townships are in their reassessment year. The authoritative schedule is on the Cook County Assessor's site. Any calendar elsewhere, including this one, is an estimate.

Can you appeal property taxes after the deadline in Cook County?

No. Once the Board of Review's window closes for your township in a given year, appeals for that tax year are barred under Illinois law (35 ILCS 200). Extremely narrow procedural exceptions exist for homeowners who never received a certified notice, but courts have upheld the deadlines. After a missed deadline, verify all exemptions are applied and calendar next year's window immediately.

What is the Cook County property tax appeal deadline for 2026?

The 2026 reassessment covers north suburban townships. The Assessor will publish township rolls on a rolling basis starting in early 2026, and each township's 30-day appeal window opens then. The Board of Review's 2026 schedule will post on its site. No definitive dates exist yet as of mid-2025; check the Assessor's site in early 2026.

How do I search for my Cook County property tax information?

Use two portals. The Cook County Assessor's site shows your assessed value, estimated market value, characteristics, and exemptions. The Cook County Treasurer's site shows actual tax bills and payment status. You need your 14-digit Property Index Number (PIN), found on your tax bill or deed, to look up either record.

How much can I save by appealing my Cook County property tax assessment?

It depends on how far off your assessment is. Board of Review data shows about 60% of residential appeals get some reduction. A 10% cut in assessed value on a $350,000 home in a 2.5% effective-rate area saves roughly $875 a year. Larger errors, especially in square footage or classification, can produce cuts of 20% to 30%. Filing costs nothing, so the downside of trying is small.

What is the Cook County equalization factor and how does it affect my bill?

The Illinois Department of Revenue sets an annual equalization factor (the 'multiplier') for Cook County to align total assessed values with statewide standards. For 2023 taxes, the factor was 2.9109. Your assessed value times this factor produces your equalized assessed value (EAV), the base for your bill. A higher multiplier raises your EAV and your tax bill even if your assessed value didn't change.

Does paying my Cook County tax bill affect my ability to appeal?

No. Paying in full waives no appeal rights. You can pay to dodge penalties and still hold a pending appeal at the Board of Review or PTAB. If the appeal wins after you've paid, the difference usually appears as a credit on a future installment bill. Always pay on time to avoid 1.5% monthly interest.

What is the Homeowner Exemption in Cook County and how much does it save?

The Homeowner Exemption cuts your equalized assessed value by $10,000. At a typical composite rate of 2.5%, that saves about $250 a year. It applies automatically after your first qualifying year but should be checked annually on your bill. If it's missing, file a corrected application through the Assessor's office. The Senior Freeze and Senior Citizen Homestead Exemption can save more for qualifying older homeowners.

How is Cook County residential property assessed compared to commercial?

Residential properties (Class 2) are assessed at 10% of estimated market value. Commercial properties (Class 5) are assessed at 25%. That 2.5x difference makes classification a big deal for mixed-use buildings. A small building wrongly classified as commercial can face a tax bill far higher than a correctly classified residential property of the same value.

How long does a Cook County Board of Review appeal take?

Most residential Board of Review appeals are decided within 3 to 9 months of filing. Commercial or high-value residential cases run longer. The decision arrives by mail and in your online Board of Review account. Appeal further to the Illinois Property Tax Appeal Board (PTAB) and add another 12 to 36 months. Most homeowners who win do so at the Board of Review without ever reaching PTAB.

What evidence do I need to win a Cook County property tax appeal?

The two strongest kinds are overvaluation evidence (recent appraisal, arm's-length sale price, or broker CMA showing market value below the Assessor's estimate) and uniformity evidence (three to five comparable properties nearby with lower assessments, pulled from the Assessor's own data). General gripes about high taxes or comparisons to purchase price don't work. The Board of Review's Rule 11 defines a valid comparable for uniformity arguments.

Can I appeal my Cook County property taxes if I didn't receive a Notice of Proposed Assessment?

Yes. You don't need to wait for the notice. The appeal window opens when the Assessor publishes the township's roll, whether or not your individual notice arrived. Check the Assessor's township appeal schedule online and look up your current assessed value to see if you're in a reassessment year and whether the window is open.

What happens if Cook County second installment tax bills are delayed?

Delays push the due date, and the Treasurer usually suspends penalty accrual for the affected period. This happened in 2021 and 2023. For homeowners, the impact is mostly cash flow. For buyers and sellers, it creates uncertainty about prorations at closing. Watch the Treasurer's site for official announcements rather than assuming the historical August due date will hold.

Sources

1. Cook County Assessor's Office, Official Website: Triennial reassessment cycle by township, Class 2 residential assessment level of 10% of market value, exemption types and applications, Home Improvement Exemption details
2. Illinois General Assembly, Illinois Property Tax Code (35 ILCS 200): Governing statute for Illinois property tax system including appeal procedures, late payment interest rate of 1.5% per month, and PTAB appeal rights
3. Lincoln Institute of Land Policy, Significant Features of the Property Tax: Cook County effective property tax rates by municipality including Harvey exceeding 6% and Cook County average around 2.1%; national median comparison
4. Illinois Department of Revenue, Cook County Equalization Factor: Cook County equalization factor of 2.9109 for 2023 tax year
5. Cook County Treasurer's Office, Property Tax Portal: First installment due March 3, 2025; second installment targeted August 1, 2025; 2023 second installment extended to December 1; payment methods
6. Cook County Board of Review, Official Website: Board of Review appeal process, Rule 11 comparable property standards, approximately 275,000 appeals filed in 2024 with about 60% of residential appeals receiving some reduction
7. Cook County Assessor's Office, Exemptions Overview: Senior Citizen Assessment Freeze Homestead Exemption income threshold of $65,000; Veterans with Disabilities Exemption range; Senior Citizen Homestead Exemption $8,000 EAV reduction
8. Illinois Property Tax Appeal Board (PTAB): PTAB appeal must be filed within 90 days of Board of Review decision; de novo hearing process for commercial property; 35 ILCS 200/16-160