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Updated 2025 Tax Year

Knox County
Property Tax Guide

Everything you need to know about property taxes in Knox 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
2.0% to 3.5% of market value, varies by taxing district combination
1st Due
Jun 1
2nd Due
Sep 1
Exemptions
5+ Available
Section 1

How Property Tax Works

Knox County, Illinois operates under a property tax system that funds essential local services including schools, public safety, infrastructure, and county operations. Property taxes are the primary revenue source for local governments and special districts throughout the county. The effective tax rate in Knox County typically ranges from approximately 2.0% to 3.5% of market value, depending on your specific location and the combination of taxing districts that serve your property.

Property tax rates vary significantly within Knox County based on the special taxing districts where your property is located, including school districts, municipalities, townships, fire protection districts, and other local governmental units. Each district levies its own portion of the total tax rate, which means properties in different areas of the county will have different total tax rates even if they have similar assessed values. The Illinois Property Tax Extension Limitation Law (PTELL) governs how much these districts can increase their levies annually.

Section 2

What Makes Up Your Tax Bill

ComponentApproximate Rate RangeDescription
County General0.20% - 0.35%County operations, courthouse, sheriff, highways
School Districts1.20% - 2.10%Elementary and high school districts (varies by district)
Township0.05% - 0.15%Township road maintenance and general assistance
Municipal0.15% - 0.45%City/village services (if within incorporated area)
Fire Protection0.10% - 0.25%Fire districts (rural areas primarily)
Library District0.05% - 0.20%Public library services
Other Districts0.05% - 0.30%Cemetery, park, community college, etc.

Note: These rates are estimates for planning purposes. The 2025 tax rates will be finalized after local budget processes are complete. Actual rates vary significantly by location within Knox County based on your specific combination of taxing districts. Contact the Knox County Clerk's office for your property's exact tax rate.

Section 3

When Are Property Taxes Due?

For the 2025/2026 tax year in Knox 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 Knox County are additional property tax assessments that occur when there are significant changes to a property during the tax year. The most common triggers include new construction, major improvements or additions, change of ownership that reveals underassessment, or removal of tax exemptions. When supplemental taxes are levied, they are calculated based on the difference between the old assessed value and the new assessed value, prorated for the portion of the tax year remaining.

For example, if you complete a $50,000 home addition in June and the assessor determines this increases your assessed value by $16,500 (at Illinois' one-third assessment ratio), you would owe supplemental taxes on that additional assessed value for the remaining portion of the tax year. With a combined tax rate of 2.5%, this would result in approximately $206 in supplemental taxes ($16,500 × 0.025 × 0.5 year remaining). Supplemental tax bills are issued separately from regular property tax bills and have their own due dates.

Example Calculation

Example 1: $300,000 Home

  • Market Value: $300,000
  • Assessed Value (33.33%): $100,000
  • Less: Homeowner Exemption: -$10,000
  • Net Taxable Value: $90,000
  • Annual Tax (2.3% rate): $2,070
  • Monthly Escrow: $173

Example 2: $600,000 Home with Credits

  • Market Value: $600,000
  • Assessed Value (33.33%): $200,000
  • Less: Homeowner Exemption: -$10,000
  • Less: Senior Homestead (if applicable): -$5,000
  • Net Taxable Value: $185,000
  • Annual Tax (2.6% rate): $4,810
  • Monthly Escrow: $401

Example 3: $1,000,000 Home

  • Market Value: $1,000,000
  • Assessed Value (33.33%): $333,333
  • Less: Homeowner Exemption: -$10,000
  • Net Taxable Value: $323,333
  • Annual Tax (2.8% rate): $9,053
  • Monthly Escrow: $754

Note: Tax credits shown require annual application and are not automatic. Actual tax rates vary by location within Knox County.

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Section 5

Escrow & Property Taxes

Most homeowners with mortgages have their property taxes collected through an escrow account managed by their lender. Your mortgage servicer estimates your annual property tax liability and divides it by 12 to determine your monthly escrow payment. This amount is collected along with your principal and interest payment each month. Lenders are required to maintain an escrow analysis annually and may adjust your monthly payment if taxes increase or decrease significantly.

Knox County property taxes are due July 21, 2025, and September 3, 2025, for the current tax year. Your lender will make these payments directly to the Knox County Collector on your behalf if you have an escrow account. It's important to verify that payments are made on time, as you remain ultimately responsible for ensuring taxes are paid even when using escrow. You can verify payments were received by checking the Knox County Collector's website or contacting their office directly.

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

Q: When are Knox County property taxes due for 2025? A: Property taxes are due July 21, 2025, and September 3, 2025. Mobile home taxes have an earlier due date of May 16, 2025.

Q: What tax credits are available and do I need to apply? A: Available tax credits include the Homeowner Exemption (up to $10,000 reduction in EAV), Owner Occupied exemption (up to $6,000 reduction in EAV), and Senior Homestead exemption ($5,000 reduction in EAV for qualifying seniors). All exemptions require application and are not automatic.

Q: How does the Homestead exemption work? A: The Homestead exemption reduces your Equalized Assessed Value (EAV) if you own and occupy your home as of January 1st. You must apply annually for this exemption through the Knox County Assessor's office.

Q: How often are properties reassessed in Knox County? A: Illinois law requires properties to be reassessed at least every four years, though Knox County may conduct assessments more frequently. The valuation date for 2025 assessments is January 1, 2025.

Q: Can I appeal my property assessment? A: Yes, you can appeal your assessment if you believe it's too high. Appeals must be filed with the Knox County Board of Review within specific deadlines, typically during the summer months when assessment notices are mailed.

Q: What are the penalties for late payment? A: Illinois law allows for penalties and interest on late property tax payments. Contact the Knox County Collector's office for current penalty rates and payment options if your taxes are overdue.

Q: Can I pay my property taxes online? A: Yes, Knox County offers online property tax payment options. Visit the Knox County Collector's website for secure online payment processing.

Q: Why do tax rates vary within Knox County? A: Your total tax rate depends on all the taxing districts that serve your property, including school districts, municipalities, townships, and special districts. Different combinations of these districts result in different total tax rates throughout the county.

Verified Sources

Backed by 10 Official Government Sources

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

01
Assessment Changesknoxcountyil.gov
02
County
Knox - County Replacement Tax Detail - Illinois.govtax.illinois.gov
03
County
Knox County Board Member Packet Regular Meeting of the ...knoxcountyil.gov
04
State
Real Estate Taxesknoxcountyil.gov
05
County
Knox County Real Estate Billsknoxcountyil.gov
06
Tax Doc
Mobile Home Tax Billknoxcountyil.gov
07
Exemptionsknoxcountyil.gov
08
Exemptions & Applicationsknoxcountyil.gov
09
Senior Citizens Infoknoxcountyil.gov
10
County
Knox County, Illinoisknoxcountyil.gov
All sources verified as of 2025 Tax Year

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