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Updated 2025 Tax Year

Warren County
Property Tax Guide

Everything you need to know about property taxes in Warren 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
Varies by district due to different taxing entities (schools, townships, municipalities, fire districts)
1st Due
Jun 1
2nd Due
Sep 1
Exemptions
5+ Available
Section 1

How Property Tax Works

Warren County, Illinois operates under the state's property tax system, which funds essential local services including schools, townships, municipalities, and county operations. Property taxes in Warren County are administered by the County Clerk, who computes annual tax assessments and prepares tax books for the County Collector to issue tax bills. The Illinois Property Tax Extension Limitation Law (PTELL) governs how tax levies can increase from year to year.

Property tax rates in Warren County vary significantly by location within the county due to different combinations of special taxing districts, including school districts, municipalities, townships, fire protection districts, and other local government entities. Each property's total tax rate represents the sum of all applicable district rates for that specific location. Property owners should expect their actual rate to differ from county averages based on their precise address and the taxing districts that serve their area.

Real estate taxes are typically due twice yearly, with due dates as close to June 1st and September 1st as possible each year. The county follows Illinois' standard assessment practices, with most residential properties assessed at 33.33% of fair market value, though this can vary by local assessment practices and property classification.

Section 2

What Makes Up Your Tax Bill

ComponentRateDescription
County GeneralVariesBasic county operations and services
School DistrictsVariesLocal elementary and high school districts
TownshipVariesTownship government services
Municipal~$0.6546*City services (where applicable)
Special DistrictsVariesFire protection, library, park districts

*Based on 2024 tax bill data for properties in municipal areas

Note: The 2025 official property tax rates for Warren County have not yet been released. Rates shown are estimates based on available 2024 data. Total effective rates typically range from 6-10% of assessed value depending on location and applicable taxing districts. Each property's rate depends on its specific combination of taxing districts. Contact the Warren County Clerk's office or check local government websites for current official rates when available.

Section 3

When Are Property Taxes Due?

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

First Installment
Jun 1
Delinquent after Dec 10
Second Installment
Sep 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 taxes in Warren County are additional property tax assessments that occur when there are changes to a property's assessed value during the tax year. Common triggers include new construction, major improvements, ownership transfers that result in reassessment, or corrections to the original assessment. The County Clerk computes these supplemental assessments based on the increased assessed value and applies the same tax rates that were used for the regular tax bill.

When supplemental taxes are issued, they represent the additional tax owed for the portion of the tax year following the change. For example, if a new addition is completed in January and adds $50,000 to the assessed value, the supplemental tax would be calculated by multiplying that additional assessed value by the applicable tax rate, then prorating it for the remaining months of the tax year. These supplemental bills are issued separately from regular tax bills and have their own due dates, typically 30 days from the issue date.

Example Calculation

Example 1: $300,000 Home

  • Market Value: $300,000
  • Assessed Value (33.33%): $100,000
  • Less Homestead Exemption: -$10,000
  • Net Taxable Value: $90,000
  • Estimated Tax Rate: 7.5%
  • Annual Tax: $6,750
  • Monthly Escrow: $563

Example 2: $600,000 Home

  • Market Value: $600,000
  • Assessed Value (33.33%): $200,000
  • Less Homestead Exemption: -$10,000
  • Net Taxable Value: $190,000
  • Estimated Tax Rate: 7.5%
  • Annual Tax: $14,250
  • Monthly Escrow: $1,188

Example 3: $1,000,000 Home

  • Market Value: $1,000,000
  • Assessed Value (33.33%): $333,300
  • Less Homestead Exemption: -$10,000
  • Net Taxable Value: $323,300
  • Estimated Tax Rate: 8.0%
  • Annual Tax: $25,864
  • Monthly Escrow: $2,155

Note: Homestead exemptions require application and are not automatic. Tax rates vary by specific taxing districts serving each property location.

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Section 5

Escrow & Property Taxes

Most mortgage lenders in Warren County require borrowers to maintain an escrow account for property tax payments, especially when the loan-to-value ratio exceeds 80%. The lender collects monthly escrow payments along with principal and interest, then pays property taxes directly to Warren County on the homeowner's behalf. Monthly escrow amounts are calculated by taking the annual property tax bill and dividing by 12, often with a small cushion to account for potential increases.

Lenders typically pay Warren County property taxes before the June 1st and September 1st due dates to avoid penalties. Property owners with escrowed taxes will receive copies of their tax bills for informational purposes, but should not pay them directly as this could result in overpayment. Each year, lenders are required to provide an escrow analysis showing how funds were collected and disbursed, and any necessary adjustments to monthly payments for the coming year. Property owners can verify that payments were made correctly by checking with the Warren County Collector's office or through online payment systems if available.

How HonestCasa Helps
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Section 6

Frequently Asked Questions

Q: When are property taxes due in Warren County for 2025? A: Real estate taxes are due as close to June 1st and September 1st as possible each year. Mobile home taxes have different deadlines, with a postmark deadline around March 4th and final due date of June 30th.

Q: What tax credits are available and do I need to apply? A: The primary credit is the Homestead Exemption, which reduces your assessed value by up to $10,000. This requires an annual application and is NOT automatic. Additional credits may be available for seniors, veterans, and disabled persons, all requiring separate applications with specific deadlines.

Q: How does the Homestead Exemption work? A: The Homestead Exemption reduces your property's Equalized Assessed Value (EAV) by up to $10,000, not your market value. You must apply for this exemption - it does not automatically apply to your property.

Q: What if I disagree with my property assessment? A: Property owners can appeal their assessments through the local Board of Review process. Contact the Warren County Clerk's office for specific deadlines and procedures, which typically occur annually during designated appeal periods.

Q: What are the penalties for late payment? A: Illinois law provides for penalties and interest on late property tax payments. Contact the Warren County Collector's office for specific penalty rates and procedures for the current tax year.

Q: Can I pay my property taxes online? A: Check with the Warren County Collector's office for current online payment options and accepted payment methods. Many Illinois counties now offer online payment systems for taxpayer convenience.

Q: Why do tax rates vary within Warren County? A: Each property's tax rate is the sum of all taxing districts that serve that location, including school districts, townships, municipalities, fire districts, library districts, and other special districts. Different combinations create different total rates.

Q: How often are properties reassessed? A: Illinois properties are subject to periodic reassessment cycles. Contact the Warren County Supervisor of Assessments for the current reassessment schedule and procedures in your township or municipality.

Verified Sources

Backed by 10 Official Government Sources

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

01
Tax Doc
Tax Information | Warrenville, IL - Official Websitewarrenville.il.us
02
County
Treasurer - Warren County ILwarrencountyil.gov
03
County
Warren County, Illinoiswarrencountyil.gov
04
2025 Filing Deadlines and Decision Mailed Dateslakecountyil.gov
05
County
Supervisor of Assessment - Warren County ILwarrencountyil.gov
06
Tax Doc
PTAX-343 Application for the Homestead Exemptionwarrencountyil.gov
07
Tax Doc
PTAX-341 Application for Returning Veterans' Homestead ...warrencountyil.gov
08
Tax Doc
PTAX-342, Application for Standard Homestead Exemption ...warrencountyil.gov
09
Table of Contentswarrencountyil.gov
10
State
PTAX-203 - Illinois Real Estatewarrencountyil.gov
All sources verified as of 2025 Tax Year

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