Tax FAQs and Glossary of Tax Terms


property tax 101

Cook County Property Tax 101 provides an overview of the Illinois Property Tax system operating in Cook County.  In an effort to increase transparency, the Cook County Clerk designed an application that identifies the role each county office plays in generating property assessments and taxes. This dynamic ArcGIS Story Map, developed in collaboration with the County Bureau of Technology, includes interactive mapping and helpful websites.  


When are taxes due?

Property taxes are due in two installments every year - an estimated installment due March 1 and a final installment due in the fall. Current taxes are paid to the Cook County Treasurer's office, which mails the tax bills to the last "Taxpayer of Record" on file with the Treasurer's office. To make sure you or your representative is listed as the current Taxpayer of Record, visit the Cook County Treasurer's website. Under Illinois law, your taxes are due and must be paid on time, whether or not you receive a tax bill.

How do I know if my taxes have been sold?

Most taxpayers receive a notice before the annual tax sale begins. The letter is sent by the Cook County Treasurer's office to inform taxpayers that balances still due will be offered for sale. Once taxes are sold, a notice prepared by the tax buyer, called a "Take Notice," is mailed by the Clerk's office. This notice is prepared and mailed within the first five months after the date of sale. The notice before the sale and the Take Notice are sent by certified mail to the last Taxpayer of Record on file with the Treasurer's office.

It is very important that the Treasurer's office have the correct information for your PIN, even if your mortgage company is responsible for paying your taxes. You can check the mailing address for the current year by logging on to the Treasurer's website.

Also, a notice on your current tax bill may provide an indication that your taxes have been sold, or that you have other taxes that are due and that may have been sold or may be available for sale at any time. Your tax bill will show annual sales only for two years after the sale.

If you know or suspect that you have delinquent taxes or that your taxes have been sold, please call the Clerk's office at (312) 603-5645 to verify the status.

What should I do if my taxes have been sold?

If your taxes have been sold, you should immediately obtain an Estimate of the Cost of Redemption. This is a calculation of the amount you need to pay to redeem the sale and remove the threat of loss of the property. Once you obtain the estimate, verify that it is for the correct PIN. You are advised to redeem the taxes immediately, as penalties and fees can increase and can multiply over time. These taxes and any fees and penalties must be paid in full; there are no payment plans applicable to redemption payments.

What should I do if I believe my taxes have been sold in error, or if I have paid my taxes and they have not been credited to my property?

You should immediately contact the Cook County Treasurer's office with any documentation you have to support your claim. You should always keep a copy of the check or money order you used to pay your taxes, as well as any receipts received that will allow you to prove that you paid the full amount on time. This will help with any dispute you have over your property tax payments. Please visit the website of the Treasurer's office or call (312) 443-5100 to review the "Sale in Error" process.

What is a PIN?

A PIN, or property index number (also called a permanent real estate index number), is a unique 14-digit number that represents a parcel of land for taxation purposes. The PIN is actually a numerical code for the legal description of the parcel, as that parcel has been defined for the purposes of real estate taxes. The formatted code points to the parcel's location on the county tax maps.

Most deeds reflect the PIN or PINs covered in the transfer of the property. Your tax bill will also show the PIN. If you need to locate a PIN, there's a search engine on the website for the Cook County Assessor's office that allows you to locate a PIN from an address. Check the photo of the property to verify that you are locating the correct parcel.

To learn how to use your PIN, visit our web page: "More About PINs".

What is a legal description?

A legal description uniquely describes a parcel of land without ambiguity. The most common legal description references lots and/or blocks within an existing subdivision number. There are also descriptions by metes and bounds, which describe in prose the geometry of a parcel's perimeter.

When a parcel lies within a platted subdivision, the legal description is usually short, because the lots described are represented by specific dimensions and boundaries on the subdivision plat. A metes and bounds description can be very lengthy and may contain bearings and distances for each line, with descriptive geometry for each curve and references to adjacent land.

How do I read a legal description card?

Click here for instructions on reading a legal description.

What do I do if I didn't receive my exemptions as a homeowner?

If you have questions regarding homeowner or senior exemptions please visit the website of the Cook County Assessor's office or call (312) 443-7550.

What do I do if I want to dispute an assessment on my property?

If you want to dispute the valuation of your property for taxation purposes, you may do so through the Cook County Assessor's office or through the Cook County Board of Review. Both have specific timetables each year for reviewing assessments in different sections of the county. You must contact each office to ensure you meet the filing deadlines. Call the Cook County Assessor's office at (312) 443-7550 or the Cook County Board of Review at (312) 603-5542.

I live in a condominium - Why does my PIN keep changing?

The initial PIN assigned to a condominium unit comes from an instrument known as the "Condominium Declaration" filed by the condominium developer. The condominium declaration automatically divides the land on which the condo is built, establishing a PIN for each unit listed in the percentage of ownership section of the declaration. In many cases, the original Condominium Declaration is merely the first phase in the developer's overall plan. Subsequent amendments to the declaration may add more units or land to the development. Additional property divisions are required as the percentages of ownership and/or the underlying description of the property change, requiring consequent changes in the PINs assigned to the units.

What documents can I obtain from the Map Unit?

For a fee, the Cook County Clerk's office can provide maps of Cook County, a tax map for a specific area or parcel, and copies of the official legal description of the property used for taxation purposes.

Are there any special programs for seniors who are having difficulty paying their taxes?

Yes. The Senior Citizen Real Estate Tax Deferral program is a tax-relief program that works like a loan. It allows qualified seniors to defer a maximum of $5,000 per tax year (this includes 1st and 2nd installments) on their primary home. The loan from the State of Illinois is paid when the property is sold, or upon the death of the participant. Specific qualifications must be met, including but not limited to: homeowners must be at least 65 by June 1 of the year in which applications are made; household income must be $55,000 or less. Applications are accepted by the Cook County Treasurer between Jan. 1 and March 1 every year. For more information, visit:

Tax Delinquency Disclaimer


Tax Redemption Terms

Certificate of Deposit for Redemption; Duplicate Certificate of Deposit for Redemption

A certification issued by the Clerk's office showing a payment deposited in the Clerk's office for the redemption of a particular tax sale on a particular property. The certification shows the name of the redeeming party, the date of payment and the various taxes, penalties, costs and fees that were collected.

Certificate of Error

A document issued by the Assessor's office that is either certified by the Assessor or approved by the court to correct an error in the tax bill. Usually, these are used to obtain missing homeowner or senior exemptions, and do not require court approval to reduce the total amount of tax due.

Certificate of Payment

A certification issued by the Clerk's office attesting to the amount of taxes billed for a particular property for a particular tax year, along with any payments credited for that tax year by the Treasurer's office.

Current Taxes

Taxes levied and due, until the date those taxes are offered at the annual tax sale.

Delinquent Taxes

Past due and unpaid taxes.

Forfeited Tax; Forfeited to the State of Illinois

Any tax upon which a judgment has been entered by the Circuit Court of Cook County and which was offered at an annual tax sale and not sold. These taxes are available to interested investors who wish to purchase them over-the-counter at the Clerk's office at any time after the annual tax sale at which they were originally offered.

Open Taxes

Delinquent or unpaid taxes from a prior year that were neither forfeited nor sold at an annual tax sale. Usually, these taxes are those that the Cook County Treasurer's office withheld from the annual sale application for judgment, due to pending action in another venue, such as a bankruptcy filing or a Certificate of Error filed with the Cook County Assessor's office.

Permanent Real Estate Index Number

An alternate name for "Property Index Number" or "PIN," which is a 14-digit number that represents a parcel of land for taxation purposes (see below).

Property Index Number or PIN

A PIN or property index number (also called "permanent real estate index number") is a unique 14-digit number assigned to a parcel of land for taxation purposes. The PIN is actually a numerical code for the legal description of the parcel, as that parcel has been defined for the purposes of real estate taxes. The formatted code points to the parcel's location on the county tax maps.


The process of repaying taxes that have been the subject of a judgment in the Circuit Court of Cook County and either sold to a tax buyer or forfeited to the State of Illinois.

Redemption Period

Statutory length of time during which taxes may be redeemed. May be extended upon direction of the tax buyer, but never more than three years from the date of sale.

Take Notice

A notice that taxes were sold, prepared by the tax buyer in a specific format required under Illinois law. Take notices are sent at two different times. The tax buyer prepares the first Take Notice and files it with the Cook County Clerk's office within 4 ½ months after the date of sale. The Clerk's office then sends the notice via certified mail. If the taxes haven't been redeemed, the tax buyer prepares a second set of Take Notices within three to six months before the last day of the redemption period. These Take Notices are served by the Cook County Sheriff's office and mailed by the Circuit Court Clerk's office.

Tax Buyer

The individual or entity that purchased the taxes at an auction conducted by the Cook County Treasurer's office, or purchased over-the-counter for forfeited taxes that were offered and not sold at the annual sale. The tax buyer acquires an interest in the property which can lead to a loss of the property if the taxes are not redeemed within the redemption period. Interest can be as high as 36 percent per year in addition to the statutory 1.5 percent interest per month on unpaid taxes.

Tax Sale

The sale of the county's tax lien to an entity or individual who may take ownership of the property if the sale is not redeemed within the permitted timeframe.

Annual Tax Sale

The tax sale conducted each year by the Cook County Treasurer's office for the taxes not paid in the just concluded tax year.

Scavenger Tax Sale

The tax sale conducted by the Cook County Treasurer's office in alternate years, offering any property that has taxes due and owed for more than three tax years.

Tax Extension Terms

Equalized Assessed Valuation

The assessed valuation of each property multiplied by the equalization factor.

Equalization Factor

A factor, established by the Illinois Department of Revenue, used to bring the aggregate value of assessments within Cook County to 33 1/3% of the estimated actual fair market value of all real property in Cook County. This factor, also called the "multiplier," is recalculated by the state each year.

Tax Levy

A taxing district's request for revenue to be obtained from the property tax.

Tax Rate

The tax levy, reduced by statutory limitations, divided by the total equalized assessed valuation of a taxing body. The tax rate is the rate per $100 of equalized assessed valuation that must be paid for the tax year in question.

Taxing District

Units of local government that are authorized to tax property within their geographic boundaries, such as school districts, park districts and municipalities.

Property tax

A tax, generally based on the value of the property, authorized by state law and used to fund many aspects of local government.


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