HonestCasa logoHonestCasa
Updated 2025 Tax Year

Boone County
Property Tax Guide

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

10 Official Sources
8 min read
Quick Facts
Tax Rate
0.85868% base county rate, total effective rates 2.5%-4% including local districts
1st Due
Jun 1
2nd Due
Sep 1
Exemptions
5+ Available
Section 1

How Property Tax Works

Boone County, Illinois operates under a property tax system that funds essential local services including schools, county government, townships, and various special districts. For the 2025 tax year, the county-wide tax rate is 0.85868%, though this represents only the base county levy. Your actual property tax rate will be significantly higher when combined with local taxing districts such as school districts, municipalities, fire protection districts, and library districts that serve your specific property location.

Property taxes in Boone County are assessed annually and paid in two installments, typically due June 1 and September 1. The total effective tax rate varies considerably by location within the county, ranging from approximately 2.5% to over 4% of assessed value depending on which combination of taxing districts serve your property. Illinois uses an assessment ratio of 33.33% of fair market value for residential properties, meaning a $300,000 home would have an assessed value of approximately $100,000 before any applicable tax credits are applied.

Section 2

What Makes Up Your Tax Bill

ComponentRate RangeDescription
County Levy0.85868%Base county services (FY 2025)
School Districts3.5% - 6.5%Elementary and high school districts vary by location
Municipal0.3% - 1.2%City/village services (if within municipal boundaries)
Township0.1% - 0.3%Township road and general assistance
Library District0.2% - 0.4%Public library services
Fire Protection0.3% - 0.8%Fire and emergency services
Park District0.1% - 0.5%Parks and recreation (where applicable)
Total Effective Rate5.35% - 10.05%Combined rate varies by specific location

Note: These rates apply to the 2025 tax year (FY 2025-2026 levy). Your actual tax rate depends on which specific taxing districts serve your property address. The county provides a tax rate lookup tool to determine your exact district combination.

Section 3

When Are Property Taxes Due?

For the 2025/2026 tax year in Boone 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 Boone County are triggered by significant changes to your property that occur during the tax year, most commonly new construction, major improvements, or ownership transfers that result in a reassessment. When the County Assessor determines that additional assessed value should be added to the tax rolls, a supplemental bill is issued to collect the pro-rated taxes for the remainder of the fiscal year.

The supplemental tax is calculated by taking the difference between your original assessed value and the new assessed value, multiplying by your property's total tax rate, then pro-rating for the number of months remaining in the tax year. For example, if you complete a $100,000 home addition in March that increases your assessed value by $33,333 (at the 33.33% assessment ratio), and your total tax rate is 6%, you would owe approximately $1,000 in supplemental taxes ($33,333 × 6% × 7/12 months remaining).

Supplemental tax bills are typically mailed within 60-90 days of the assessment change and become due 30 days from the bill date. These taxes are in addition to your regular tax installments and cannot be appealed separately from the underlying assessment that triggered them.

Example Calculation

Example 1: $300,000 Home with Homeowner Exemption

  • Market Value: $300,000
  • Assessed Value (33.33%): $100,000
  • Homeowner Exemption Applied: -$10,000 (requires application)
  • Net Taxable Value: $90,000
  • Tax Rate (example district): 5.85%
  • Annual Tax: $5,265
  • Monthly Escrow: $439

Example 2: $600,000 Home with Multiple Credits

  • Market Value: $600,000
  • Assessed Value (33.33%): $200,000
  • Homeowner Exemption: -$10,000 (requires application)
  • Senior Citizens Assessment Freeze: Additional savings (if qualified, requires application)
  • Net Taxable Value: $190,000
  • Tax Rate (example district): 6.25%
  • Annual Tax: $11,875
  • Monthly Escrow: $989

Example 3: $1,000,000 Home

  • Market Value: $1,000,000
  • Assessed Value (33.33%): $333,333
  • Homeowner Exemption: -$10,000 (requires application)
  • Net Taxable Value: $323,333
  • Tax Rate (example district): 7.15%
  • Annual Tax: $23,118
  • Monthly Escrow: $1,927

Note: All tax credits require separate applications and are not automatically applied. Rates shown are examples - your actual rate depends on your specific taxing district combination.

See How Taxes Affect Your Payment

Property taxes are just part of your total monthly cost. Get the full picture.

Calculate Now
Section 5

Escrow & Property Taxes

Most mortgage lenders in Boone County require borrowers to establish an escrow account to ensure property taxes are paid on time. Your lender will collect 1/12th of your estimated annual property tax bill with each monthly mortgage payment, then pay your taxes directly to the county when they become due. Lenders typically collect a 2-month cushion to account for potential tax increases.

Property tax bills in Boone County are mailed to the property address by default, but when an escrow account exists, duplicate bills are sent to the mortgage servicer. The first installment is due June 1, and the second installment is due September 1. If tax bills are mailed late (after May 1), the first installment due date extends to 30 days after the bill date. Lenders monitor these due dates and typically pay a few days early to ensure on-time payment.

Each year, lenders must provide an escrow analysis comparing collected amounts with actual tax payments. If taxes increase significantly, your monthly escrow payment may be adjusted upward, and you may owe a shortage. If taxes decrease or if the lender collected too much, you'll receive a refund. Property owners should review their tax bills annually even with escrow accounts to verify accuracy and ensure all applicable tax credits are being applied.

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 Boone County for the current tax year? A: For the 2025 tax year, the first installment is due June 1, 2025, and the second installment is due September 1, 2025. If bills are mailed after May 1, the first installment due date extends to 30 days after the bill date.

Q: What tax credits are available and do they apply automatically? A: The Homeowner Exemption reduces taxable assessed value by up to $10,000 and requires an annual application. Senior Citizens may qualify for assessment freeze programs. Veterans may be eligible for disabled veterans exemptions. None of these credits are automatic - all require separate applications filed with the County Assessor's office.

Q: How does the Homestead Exemption work? A: Illinois offers a Homeowner Exemption (not "homestead") that reduces your property's equalized assessed value by up to $10,000 for owner-occupied properties. This is a true exemption that lowers the taxable value, not a credit that caps assessment increases. You must apply annually with the County Assessor, typically by January 31st.

Q: When are properties reassessed in Boone County? A: Boone County conducts comprehensive reassessments every four years as part of Illinois's quadrennial assessment cycle. Between general reassessments, properties may be individually reassessed due to ownership changes, new construction, or appeals. The next county-wide reassessment is scheduled for tax year 2026.

Q: How do I appeal my property assessment? A: Assessment appeals must be filed with the Boone County Board of Review by 30 days after the assessment notice date, typically in late summer. You can appeal online, by mail, or in person. You'll need comparable sales data or professional appraisal evidence to support your claim that the assessed value exceeds 33.33% of fair market value.

Q: What are the penalties for late property tax payments? A: Late payments incur interest charges of 1.5% per month (18% annually) starting the day after the due date. If taxes remain unpaid for two years, the property becomes eligible for tax sale. First installment penalties begin June 2nd, and second installment penalties begin September 2nd.

Q: Can I pay my property taxes online? A: Yes, Boone County offers online payment options through their official website. You can pay by electronic check or credit card, though credit card payments typically include a convenience fee. Online payments must be submitted by 11:59 PM on the due date to be considered on time.

Q: Why do I pay different tax rates than my neighbor? A: Tax rates vary significantly within Boone County based on which combination of taxing districts serve your property. Two homes on the same street may be in different school districts, fire protection districts, or library districts, resulting in different total tax rates. The county provides a district lookup tool to identify which taxing bodies serve your specific address.

See the Full Picture of Your Home Costs

Property taxes are just one piece of homeownership. HonestCasa helps you understand your total monthly cost and explore safe ways to access your home equity.

Total Monthly Cost

Mortgage + taxes + insurance + HOA

Equity Growth

Track how your equity grows over time

Safe Equity Access

Options for projects or debt payoff

Free • No credit check • 2-minute estimate