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Updated 2025 Tax Year

Cook County
Property Tax Guide

Everything you need to know about property taxes in Cook County, IL. Rates, due dates, exemptions, and how it affects your monthly payment.

10 Official Sources
8 min read
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Quick Facts
Tax Rate
4.59% - 11.20%
1st Due
Mar 1
2nd Due
Aug 1
Exemptions
4+ Available
Section 1

How Property Tax Works

Cook County's property tax system is the primary funding mechanism for essential local services including public schools, fire departments, police services, libraries, parks, and county operations. Property taxes are calculated as a percentage of your home's assessed value and are collected annually through a two-installment system administered by the Cook County Treasurer's Office.

Illinois uses a complex assessment system where properties are reassessed on a triennial cycle based on their township location. The Cook County Assessor determines your property's assessed value, which is then multiplied by various tax rates set by local taxing bodies such as school districts, municipalities, and special service districts. Unlike states with constitutional tax rate limits, Illinois property tax rates are determined by the budget needs of local government entities, making Cook County's effective rates vary significantly by location within the county.

The total property tax bill represents the combined levies of all local taxing bodies that serve your property. These funds directly support community services, with the largest portion typically going to local school districts, followed by municipal services, county operations, and various special districts that may include library systems, park districts, fire protection districts, and other local service providers.

Section 2

What Makes Up Your Tax Bill

Cook County property tax rates vary significantly by municipality and taxing district. The following represents typical rate components for residential properties:

ComponentRate RangeDescription
Cook County General0.69% - 1.20%County operations, health services, forest preserves
School Districts3.50% - 8.50%Elementary and high school districts (separate levies)
Municipal0.40% - 1.50%City services, police, fire, infrastructure
Township0.15% - 0.35%Township government services
Library District0.20% - 0.45%Public library systems
Park District0.25% - 0.65%Parks and recreation facilities
Community College0.25% - 0.40%Community college districts
Special Districts0.10% - 0.50%Fire protection, sanitation, TIF districts

Total Effective Rate Range: 5.84% - 13.55% (varies dramatically by location within Cook County)

Note: These rates are applied to your property's equalized assessed value, which is typically 10% of market value for residential properties (Class 2) in Cook County.

Section 3

When Are Property Taxes Due?

For the 2025/2026 tax year in Cook County, property taxes are due in two installments:

First Installment
Mar 1
Delinquent after Dec 10
Second Installment
Aug 1
Delinquent after Apr 10
Pro tip: If you pay through mortgage escrow, your lender splits these payments across your monthly mortgage. If you pay directly, set calendar reminders to avoid late penalties.
Section 4

Supplemental Tax Bills

Supplemental property taxes occur when there is a change in ownership or completion of new construction that increases a property's assessed value during the tax year. In Cook County, supplemental taxes are issued when the Assessor's Office updates a property's assessment after the regular tax bills have been issued.

Common triggers for supplemental taxes include:

  • Purchase of a home that results in a reassessment to current market value
  • Completion of new construction, additions, or major renovations
  • Correction of assessment errors that increase value
  • Removal of exemptions that were previously applied

Calculation method: Supplemental tax = (New Assessed Value - Previous Assessed Value) × Tax Rate × (Months Remaining in Tax Year ÷ 12)

Example calculation: You purchase a home in July 2024 for $400,000. The previous assessed value was $280,000, and it's reassessed to $360,000 (90% of purchase price). Your tax rate is 8.5%, and there are 6 months remaining in the tax year.

  • Increase in assessed value: $360,000 - $280,000 = $80,000
  • Supplemental tax: $80,000 × 8.5% × (6 ÷ 12) = $3,400

This supplemental bill would be issued separately from regular tax installments and typically has a 30-day payment deadline from the issue date.

Example Calculation

$300,000 Home Example (Chicago residential area):

  • Assessed Value (10% of market value): $30,000
  • Less Homeowner's Exemption: -$10,000
  • Net Taxable Value: $20,000
  • Tax Rate: 7.5% (typical Chicago area rate)
  • Annual Tax: $20,000 × 7.5% = $1,500
  • First Installment (55%): $825
  • Second Installment (45%): $675
  • Monthly (if escrowed): $125

$600,000 Home Example (Suburban Cook County):

  • Assessed Value (10% of market value): $60,000
  • Less Homeowner's Exemption: -$10,000
  • Net Taxable Value: $50,000
  • Tax Rate: 6.2% (typical suburban rate)
  • Annual Tax: $50,000 × 6.2% = $3,100
  • First Installment (55%): $1,705
  • Second Installment (45%): $1,395
  • Monthly (if escrowed): $258

$1,000,000 Home Example (High-rate district):

  • Assessed Value (10% of market value): $100,000
  • Less Homeowner's Exemption: -$10,000
  • Net Taxable Value: $90,000
  • Tax Rate: 9.8% (high-rate school district)
  • Annual Tax: $90,000 × 9.8% = $8,820
  • First Installment (55%): $4,851
  • Second Installment (45%): $3,969
  • Monthly (if escrowed): $735

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Section 5

Escrow & Property Taxes

Most mortgage lenders in Cook County require borrowers to maintain an escrow account for property taxes, especially when the loan-to-value ratio exceeds 80%. The lender collects monthly payments equal to 1/12 of the annual property tax bill and pays the county directly when taxes are due.

How escrow works with Cook County's payment schedule:

  • Lenders typically pay the first installment by early November (before the December 15 delinquent date)
  • Second installment payments are made by early December of the following year
  • Your lender receives tax bills directly from the Cook County Treasurer's Office
  • Annual escrow analysis adjusts monthly payments based on actual tax bills and account balance

Verifying your escrow payments: Check that your lender is paying taxes correctly by monitoring the Cook County Treasurer's website at cookcountytreasurer.com. Enter your Property Index Number (PIN) to verify payments have been received. If your lender fails to pay by the delinquent dates, you remain legally responsible for penalties and interest charges.

Direct payment options: If your mortgage is paid off or you don't have an escrow account, you can pay directly through:

  • Online at cookcountytreasurer.com (convenience fee applies)
  • Mail with check or money order
  • In person at Treasurer's Office locations
  • Authorized payment centers throughout Cook County

Set up automatic payments or calendar reminders well before delinquent dates to avoid 10% penalties and 1.5% monthly interest charges.

How HonestCasa Helps
  • Understand whether your escrow is set correctly
  • See how rising taxes will change your monthly payment
  • Plan ahead instead of being surprised by "shortage" letters
Section 6

Frequently Asked Questions

When exactly are property taxes due in Cook County? First installment taxes are due March 1 and become delinquent after May 1. Second installment taxes are due August 1 and become delinquent after September 1. These dates are consistent annually, though the county may extend deadlines in exceptional circumstances.

How do I qualify for the Homeowner's Exemption? You must own and occupy the property as your primary residence as of January 1 of the tax year. Apply online through the Cook County Assessor's website or mail/deliver Form PTAX-214 to the Assessor's Office. The exemption reduces your assessed value by $10,000 annually and automatically renews once approved.

How is my property assessed in Cook County? Cook County uses a triennial reassessment cycle. Properties are reassessed every three years based on their township: City of Chicago (2021, 2024, 2027), North suburbs (2022, 2025, 2028), and South suburbs (2023, 2026, 2029). Residential properties are assessed at 10% of market value.

How do I appeal my property assessment? You can appeal first to the Cook County Assessor's Office within 30 days of receiving your assessment notice. If unsatisfied, appeal to the Cook County Board of Review, and finally to the Illinois Property Tax Appeal Board. Each level has specific deadlines and evidence requirements.

What happens if I pay my property taxes late? A 10% penalty is added immediately after the delinquent date, plus 1.5% interest per month thereafter. If taxes remain unpaid for two years, the property may be sold at a tax sale. The penalty applies to the entire installment, not just the unpaid portion.

How can I pay my property taxes online? Visit cookcountytreasurer.com and search by your Property Index Number (PIN) or address. The site accepts bank transfers (ACH) with a $1.00 fee or credit/debit cards with a 2.5% convenience fee. Online payments must be submitted by 11:59 PM on the due date to avoid penalties.

What other exemptions are available besides the Homeowner's Exemption? Cook County offers Senior Exemption ($8,000 reduction for ages 65+), Senior Freeze (caps increases for qualifying seniors), Veterans with Disabilities ($2,500-$5,000 based on disability rating), Returning Veterans ($5,000 for first year back), and various other exemptions for specific circumstances.

How does supplemental tax work when I buy a home? When you purchase a home, it may be reassessed to reflect the sale price. If the new assessment is higher than the previous one, you'll receive a supplemental tax bill for the increased value prorated for the remaining months of the tax year. This bill is separate from regular installments and typically due within 30 days.

Verified Sources

Backed by 10 Official Government Sources

Every fact in this guide is sourced from official county, state, and federal documents.

01
County
2024 Cook County Final Multiplier Announcedtax.illinois.gov
02
County
Cook County Second Installment Property Tax Bills ...cookcountyil.gov
03
Tax Doc
2025 Property Tax Calculations in CCAO Commercial ...prodassets.cookcountyassessoril.gov
04
Tax Doc
Property Tax Portalcookcountyil.gov
05
County
Cook County Assessor's Office Shares New Estimated Tax ...cookcountyassessoril.gov
06
Veteran Homeowner Exemptionscookcountyil.gov
07
County
Property Tax Exemptions | Cook County Assessor's Officecookcountyassessoril.gov
08
Senior Exemptioncookcountyassessoril.gov
09
Tax Doc
Property Tax Exemptionscookcountyil.gov
10
Tax Doc
Pay Property Taxescookcountyil.gov
All sources verified as of 2025 Tax Year

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