Question 1

When is the deadline to appeal my Cook County property taxes?

Accepted Answer

There is no single county-wide deadline — it depends on your township. The Cook County Assessor opens each of the 38 townships for roughly six weeks on a rolling schedule through the year, and the deadline is a hard date printed on your Reassessment Notice. 6 townships are open right now.
Find your township’s exact window on the deadlines-by-township table. If the Assessor’s window has already closed, you get a second chance: the Board of Review opens the same township later, with its own separate deadline.

Question 2

How do I appeal my Cook County property taxes?

Accepted Answer

You appeal in up to two free stages: first to the Cook County Assessor during your township’s open window, then, if needed, to the Cook County Board of Review. You file as the property owner, attach comparable properties or recent sales as evidence, and submit online. Neither body charges to file.
The full walkthrough covers each click. Read the step-by-step guide →

Question 3

How long does a Cook County property tax appeal take?

Accepted Answer

Filing takes about 30 minutes. The decision takes longer: each body reviews a township’s appeals only after that township’s window closes, so a decision typically arrives weeks to a few months after you file. Any reduction shows up on a later tax bill, not immediately.

Question 4

Can I appeal my Cook County property taxes every year?

Accepted Answer

Yes. You can appeal every year, not only in the triennial year your township is reassessed. Cook reassesses each township once every three years, but the Assessor and the Board of Review both open annually, so you can file in any year your assessment is too high.
The reassessment year is the most important one to check, because a new over-assessment can lock in for three years if you do not challenge it. An appeal in an off-year is equally valid and equally free.

Question 5

What is a Cook County Reassessment Notice?

Accepted Answer

A Reassessment Notice is the letter the Cook County Assessor mails when it sets a new assessed value for your property — normally once every three years, in your township’s reassessment year. It states your new assessed value and the hard deadline to appeal it. It is not a bill.
The notice is your cue to check whether the new value is too high before it locks in for the next three years. Its appeal deadline is the binding one for the Assessor stage — confirm it against your township’s window.

Question 6

How often is my property reassessed in Cook County?

Accepted Answer

Once every three years. Cook County reassesses on a triennial rotation across three groups — the City of Chicago, the north and northwest suburbs, and the south and west suburbs — one group each year. Your township’s reassessment year is when your assessed value is most likely to change.
Each township page shows which group your township is in and when it was last and will next be reassessed. You can still appeal in the two off-years, but the reassessment year is the one to watch.

Question 7

Is it worth appealing property taxes in Cook County?

Accepted Answer

For most over-assessed homeowners, yes. Filing is free at both county stages, it takes about 30 minutes with the right comparables, and appealing does not raise your assessment at the Assessor. The real question is not whether it is worth trying — it costs nothing to file — but whether your home is actually over-assessed.
Cook County over-assessment is structural: mass appraisal values hundreds of thousands of parcels by formula, so individual homes routinely land above comparable properties. If a comparison to similar nearby homes shows you are high, an appeal has a real basis. If you are already at or below your peers, appealing is unlikely to help — and it is honest to say so.

Question 8

How do I know if my Cook County home is over-assessed?

Accepted Answer

You are over-assessed when your assessment is high relative to comparable properties — the “uniformity” standard the appeal system uses. In practice: compare your assessed value per square foot to similar nearby homes. If yours is materially higher than your neighbors’ median, you have a case.
Measured across the public roll, about 120,000 Cook County dwellings sit far enough above their peers to be strong appeal candidates. Whether your specific home is one of them is a per-parcel question — check your address to see your assessment against comparable homes.

Question 9

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

Accepted Answer

It varies with how over-assessed you are, but the savings are real and recurring. Among strongly over-assessed Cook County homes, the median achievable annual saving is about $1,714 for a single-family house and $809 for a condo — every year until the next reassessment, not once.
Because you file your own appeal on the free county portal, you keep 100% of that saving. A contingency service would take a quarter to a half of the first year. Check your address to see your own estimate.

Question 10

How do I find comparable properties for my Cook County appeal?

Accepted Answer

For a uniformity appeal, comparables are nearby homes similar to yours in size, age, and style that the county assesses lower per square foot than yours — the assessments themselves are the evidence. For a market-value appeal, comparables are recent arms-length sales of similar homes below your assessed market value.
Good comparables are close by (same neighborhood and township), similar in living area and construction, and recent for sales. The strongest residential cases in Cook are usually uniformity cases. Check your address to see the comparable set on your own home.

Question 11

What is the difference between a uniformity appeal and a market-value appeal?

Accepted Answer

A uniformity appeal argues your home is assessed higher than comparable homes — you are not disputing what it is worth, only that the county treats similar properties more favorably. A market-value appeal argues your assessed value is above what the home would actually sell for, using recent sales as evidence.
Most winning residential appeals in Cook County are uniformity cases, because assessments of comparable homes are public and easy to line up. A market-value case is stronger when you have a recent purchase or nearby sales clearly below your assessment.

Question 12

Should I use assessed comparables or recent sales for my appeal?

Accepted Answer

Use assessed comparables for a uniformity appeal and recent sales for a market-value appeal — and use whichever tells the stronger story for your home. For most Cook County houses and condos, assessed comparables (the uniformity approach) are the more reliable path, because the data is public and directly comparable.
If you bought recently below your assessed market value, or several similar homes nearby just sold low, lead with sales. You can present both.

Question 13

What evidence do I need to appeal my property taxes in Cook County?

Accepted Answer

For a uniformity appeal: a short list of comparable properties assessed lower per square foot than yours. For a market-value appeal: recent arms-length sales of similar homes below your assessed market value. For a condition appeal: dated photographs of damage or deferred maintenance that lower your home’s value.
You do not need an appraisal for a typical residential appeal. A tight set of three to six well-matched comparables, plus a one-paragraph statement of why the assessment is excessive, is what wins.

Question 14

How much does it cost to appeal property taxes in Cook County?

Accepted Answer

Filing with the Cook County Assessor and the Board of Review is free — the county charges nothing to appeal. ChonkHub charges a one-time $49.15 to build your evidence packet; you file it yourself and keep 100% of any reduction. No percentage of your savings, no subscription.
That is the difference from contingency services, which take 25–50% of your first-year savings every year they represent you. Because you file on the free county portal, the only cost is the one-time packet, and every dollar saved stays with you.

Question 15

Do I need a lawyer to appeal my property taxes in Cook County?

Accepted Answer

If you own your home individually (in your own name or jointly with family), no — you can file your own appeal, and most residential appeals are self-filed. But if the property is owned by a corporation, LLC, trust, or other legal entity, the Cook County Board of Review generally requires it to be represented by a licensed attorney; an entity cannot represent itself.
This distinction is exact and often missed. A house in your personal name is a self-file case. The same house transferred into an LLC or land trust is, at the Board of Review, an attorney matter — an entity appearing without counsel can have its appeal dismissed. If your property is entity-owned, consult an attorney rather than self-filing.

Question 16

Flat fee vs. contingency: what is the better way to appeal Cook County taxes?

Accepted Answer

A contingency service takes a percentage of your savings — commonly 25–50% of the first year, sometimes every year — in exchange for handling the appeal. A flat-fee self-file model charges once and you keep everything the appeal saves. For a typical residential appeal, the self-file model keeps far more money in your pocket over time.
Contingency can make sense for complex commercial cases that genuinely need professional representation. For a house or condo where the evidence is public comparables, paying a recurring share of your own tax savings is the expensive option.

Question 17

Are property tax appeal services worth it in Cook County?

Accepted Answer

It depends on what you are paying for. The two things that win a residential appeal — public comparable assessments and a filing on the free county portal — are things a homeowner can do directly. A service is worth it when it saves you the work of finding good comparables and building the packet, but not when it charges a recurring share of savings you could have kept.
The value is in the evidence and the guidance, not in someone filing a form you are allowed to file yourself. That is why ChonkHub charges once for the packet and lets you keep 100%.

Question 18

What is an alternative to Ownwell for Cook County property tax appeals?

Accepted Answer

Ownwell and similar services file on your behalf for a percentage of your savings. The alternative is the self-file model: you get the same evidence — comparable properties and the assessment math — build the packet once for a flat fee, and file it yourself on the county’s free portal, keeping 100% of the reduction.
Both get you to an appeal. The difference is who keeps the savings and how transparent the process is. If you would rather not hand over a recurring share of your own tax relief, a flat-fee self-file service is the alternative.

Question 19

What does “keep 100%” mean for a property tax appeal?

Accepted Answer

It means no one takes a cut of your tax savings. Because you file your own appeal on the free county portal, there is no contingency fee — every dollar the reduction saves you stays with you, this year and every year until your next reassessment. The only cost is the one-time $49.15 to build your evidence packet.

Question 20

What is the difference between the Assessor and the Board of Review?

Accepted Answer

They are two separate Cook County authorities and two separate appeal stages. The Assessor sets your property’s assessed value and is the first place you appeal. The Board of Review is an independent, separately elected body that hears appeals after the Assessor — a second, fresh chance to reduce your assessment, even if the Assessor already ruled.
Both stages are free, and you can use both in the same year. Their windows differ: the Assessor opens each township first, and the Board of Review opens that township later, after the Assessor certifies. Many homeowners who get little from the Assessor succeed at the Board of Review.

Question 21

What happens after I file with the Board of Review?

Accepted Answer

The Board of Review reviews your evidence, may request a hearing, and issues a written decision after your township’s window closes. A reduction lowers the assessed value used for your next tax bill. If the Board denies you or you still disagree, you can appeal further to the Illinois Property Tax Appeal Board (PTAB) or file in the Circuit Court of Cook County.
Decisions are not instant — the Board works through a township’s appeals after it closes, so expect weeks to months. Any reduction flows through to a later tax bill, and you keep the full savings.

Question 22

What is PTAB, the Illinois Property Tax Appeal Board?

Accepted Answer

PTAB is a state-level board that hears property-tax assessment appeals after the county Board of Review. If the Cook County Board of Review denies you or does not reduce your assessment enough, you can appeal to PTAB (or, alternatively, to the Circuit Court of Cook County). It is a further step, not the first one.
Most homeowners resolve their assessment at the Assessor or Board of Review stage. PTAB matters when you have a strong case that the county stages rejected and you are willing to pursue a longer state-level process.

Question 23

What is a Certificate of Error in Cook County?

Accepted Answer

A Certificate of Error is a way to correct a factual mistake on your assessment — like a missing homeowner exemption or wrong square footage — even outside the normal appeal window, and often for prior tax years. The Assessor issues it and the Board of Review certifies it. It fixes errors of fact, not disagreements about value.
If you simply think your value is too high, that is an appeal. If the county has a fact wrong or you were owed an exemption you never received, a Certificate of Error is the right tool.

Question 24

What are the odds of winning a Cook County property tax appeal?

Accepted Answer

Better than most homeowners assume, and the two stages compound. Across the county’s own records, roughly 25% of appeals to the Assessor win a reduction, and the Board of Review — the second stage — has reduced assessments in about 32% of cases. A well-supported appeal with good comparables does better than the average.
The odds are highest when your evidence is strong: close, similar comparables assessed below your home. A hopeful appeal with weak comparables is what pulls the average down. Check your address to see whether your comparables support a case.

Question 25

Can appealing raise my property assessment?

Accepted Answer

Filing an appeal with the Cook County Assessor does not raise your assessment — the Assessor does not increase values on appeal. The Board of Review has authority to increase an assessment, but does so only rarely and only after notice. For a typical residential appeal supported by comparables, the practical downside is close to zero.

Question 26

How do I appeal property taxes on a Cook County condo?

Accepted Answer

A condo appeal works the same way as a house, on the uniformity standard, but the comparables are other units in your building and in comparable buildings. Because units in one building share a structure, the county’s assessments across those units are the natural evidence — if your unit is assessed high relative to comparable units, you have a case.
Condo owners can appeal individually; you do not need the whole association to act. Check your unit to see how it compares to others in your building.

Question 27

Can I appeal property taxes on a home owned by an LLC or trust?

Accepted Answer

Yes, but usually not by yourself. If your property is held by an LLC, corporation, or other entity, the Cook County Board of Review generally requires it to be represented by a licensed attorney — an entity cannot appear on its own behalf. A simple living trust is sometimes treated more like individual ownership, but entity ownership is the case to be careful with.
If your home is in an LLC or corporation, plan on an attorney for the Board of Review stage rather than self-filing. ChonkHub’s self-file path is built for individually-owned homes; entity-owned property should consult counsel.

Question 28

What is the difference between a homeowner exemption and an appeal?

Accepted Answer

They are separate ways to lower your bill, and you should pursue both. An exemption (like the Homeowner or Senior exemption) reduces the taxable value of your home if you qualify — you apply for it through the Assessor. An appeal challenges the assessed value itself as too high. One is about eligibility; the other is about accuracy.
Make sure you are receiving every exemption you qualify for and appeal an over-assessment — they stack. Missing an exemption you were owed can also be fixed with a Certificate of Error.

Question 29

Do I qualify for a senior or other Cook County exemption?

Accepted Answer

Cook County offers several exemptions that lower your tax bill — the Homeowner exemption for owner-occupants, plus Senior, Senior Freeze, Persons with Disabilities, Veterans, and Home Improvement exemptions for those who qualify. Eligibility and application run through the Cook County Assessor, separately from an appeal.
Exemptions and an appeal are independent, so pursue both. Check your eligibility and apply through the Assessor, and appeal separately if your assessment is too high.

Question 30

What happens if I miss my Cook County appeal deadline?

Accepted Answer

If you miss the Assessor’s deadline for your township, you are not out of options — the Board of Review opens the same township later, with its own separate window, and you can file there. If you miss both, you generally wait for the next year. A factual error, though, may still be fixable any time through a Certificate of Error.
Because the two stages have different deadlines, a missed Assessor window is recoverable. Watch your township’s Board of Review opening and file then.

Cook County Property Tax Appeal — Questions & Answers

Deadlines & how it works

Am I over-assessed — and is it worth it?

Evidence & comparables

Cost & representation

The Assessor, the Board of Review & beyond

Odds, risk & outcomes

Condos, LLCs, exemptions & special cases