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Updated 2025 Tax Year

DeKalb County
Property Tax Guide

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

10 Official Sources
8 min read
Quick Facts
Tax Rate
Varies significantly by location due to different taxing districts - contact DeKalb County Supervisor of Assessments for specific rates
Exemptions
5+ Available
Section 1

How Property Tax Works

DeKalb County, Illinois operates under a property tax system that funds essential local services including schools, county government, municipalities, fire protection districts, and library services. Property taxes are calculated based on the Equalized Assessed Value (EAV) of your property, which is typically assessed at one-third of fair market value. The Illinois Property Tax Extension Limitation Law (PTELL) governs how tax extensions are calculated and limits increases for most taxing bodies.

The effective property tax rate in DeKalb County varies significantly by location within the county due to different combinations of special taxing districts, school districts, municipalities, and township services. Based on available data, property owners can expect rates that align with Illinois's statewide average of approximately 2.27%, though your specific rate will depend on which taxing districts serve your property. Property taxes are collected in two installments annually, typically due June 1st and September 1st, and fund critical services that maintain property values and community infrastructure.

Section 2

What Makes Up Your Tax Bill

The following represents the general tax rate structure for DeKalb County properties, though actual rates vary by specific taxing district combinations:

ComponentApproximate RateDescription
DeKalb County0.967%County general operations, health services, highway maintenance
Forest Preserve0.069%Forest preserve district operations and maintenance
School DistrictsVaries by districtElementary, high school, and community college districts
MunicipalVaries by city/villageMunicipal services for incorporated areas
TownshipVaries by townshipRoad maintenance, general assistance, assessor functions
Fire ProtectionVaries by districtFire and emergency services for applicable areas
Library DistrictVaries by districtPublic library services where applicable

Note: These rates apply to the 2024 tax year (collected in 2025). Your actual combined rate depends on which specific taxing districts serve your property address. Contact the DeKalb County Supervisor of Assessments at (815) 895-7149 for your property's exact taxing district combination.

Section 3

When Are Property Taxes Due?

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

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 DeKalb County are additional property tax assessments that occur when there are changes to a property's assessed value outside the regular assessment cycle. Common triggers include new construction completion, property improvements that add significant value, ownership transfers that prompt reassessment, or corrections to previous assessment errors.

When supplemental taxes are issued, they cover the difference between the previously assessed value and the new assessed value, prorated for the portion of the tax year affected. For example, if you complete a $50,000 home addition in March and it increases your assessed value by $16,667 (at the one-third assessment ratio), you would owe supplemental taxes on that additional assessed value for the remaining nine months of the tax year. The supplemental bill would calculate the annual tax on the $16,667 increase and charge you 75% (9/12 months) of that amount, due within 30 days of the bill date.

Example Calculation

Example 1: $300,000 Home Value

  • Market Value: $300,000
  • Assessed Value (33.3%): $100,000
  • Less: Homestead Exemption: -$12,500 (schools), -$10,000 (county)
  • Net Taxable Value: ~$85,000 (average after exemptions)
  • Annual Tax (at 2.5% effective rate): $2,125
  • Monthly Escrow: $177

Example 2: $600,000 Home Value

  • Market Value: $600,000
  • Assessed Value (33.3%): $200,000
  • Less: Homestead Exemption: -$12,500 (schools), -$10,000 (county)
  • Net Taxable Value: ~$185,000 (average after exemptions)
  • Annual Tax (at 2.5% effective rate): $4,625
  • Monthly Escrow: $385

Example 3: $1,000,000 Home Value

  • Market Value: $1,000,000
  • Assessed Value (33.3%): $333,333
  • Less: Homestead Exemption: -$12,500 (schools), -$10,000 (county)
  • Net Taxable Value: ~$318,000 (average after exemptions)
  • Annual Tax (at 2.5% effective rate): $7,950
  • Monthly Escrow: $663

Note: Homestead exemptions require annual application and are not automatic. Actual rates vary by specific taxing districts. Examples use estimated effective rates for illustration purposes.

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Section 5

Escrow & Property Taxes

Most mortgage lenders in DeKalb County require borrowers to maintain an escrow account for property taxes, especially when the loan-to-value ratio exceeds 80%. Your lender collects monthly escrow payments along with your mortgage payment and pays your property tax bills directly to the county when due. The monthly escrow amount is calculated by taking your annual property tax bill, adding anticipated increases, plus a two-month cushion as allowed by federal law, then dividing by 12.

Lenders typically conduct annual escrow analyses and will adjust your monthly payment if there's a shortage or surplus. Since DeKalb County property taxes are due in two installments (June 1st and September 1st), your lender will receive and pay both bills on your behalf. You should receive copies of the tax bills and payment confirmations from your lender. If you pay your own taxes without escrow, ensure you budget for both installments and remember that late payments incur penalties and interest charges that begin accruing the day after the due date.

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 property taxes due in DeKalb County? A: Property taxes are due in two installments: typically June 1st for the first installment and September 1st for the second installment. If tax bills are mailed after May 1st, the first installment is due 30 days after the bill date.

Q: What is the Homestead Exemption and how do I apply? A: The Homestead Exemption reduces your assessed value by $12,500 for school taxes and $10,000 for county levies (excluding bonds). This is NOT automatic - you must apply annually with the DeKalb County Supervisor of Assessments. The exemption applies to your primary residence only.

Q: Are there other tax credits available? A: Yes, Illinois offers several tax credits that require application, including the Senior Citizens Homestead Exemption, Senior Citizens Assessment Freeze, Veterans with Disabilities Exemption, and Disabled Persons Homestead Exemption. Contact the Supervisor of Assessments at (815) 895-7149 for applications and eligibility requirements.

Q: How often are properties reassessed in DeKalb County? A: Illinois law requires properties to be reassessed every four years, though the county may conduct interim assessments for new construction, improvements, or significant market changes.

Q: What happens if I pay my property taxes late? A: Late payments incur penalties and interest. Interest begins accruing the day after the due date at a rate set annually by the Illinois Department of Revenue. Additionally, a penalty of 1.5% per month applies to delinquent taxes.

Q: Can I pay my property taxes online? A: Yes, DeKalb County typically offers online payment options. Check the county treasurer's website or contact the Treasurer's office for current online payment methods and any associated fees.

Q: How do I appeal my property assessment? A: Assessment appeals must be filed with the DeKalb County Board of Review during their annual appeal period, typically in summer/early fall. You'll need evidence supporting your claim that your assessment is incorrect.

Q: Why do tax rates vary within DeKalb County? A: Your total tax rate depends on which combination of taxing districts serve your property, including school districts, municipalities, townships, fire districts, and library districts. Different areas have different service providers, resulting in varying total tax rates.

Q: What is PTELL and how does it affect my taxes? A: The Property Tax Extension Limitation Law limits how much most taxing bodies can increase their total tax extension each year, typically to the rate of inflation or 5%, whichever is less. This helps control property tax growth but doesn't prevent increases due to rising property values.

Q: Can I get a partial year exemption if I move during the year? A: Homestead exemptions typically apply to the entire tax year based on January 1st ownership and occupancy. Contact the Supervisor of Assessments to discuss your specific situation if you purchased a home during the year.

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