Property Tax in Williamson County, Illinois (2026)
Last reviewed:
| Area | Effective Rate | Tax on $300K Home | Tax on $500K Home |
|---|---|---|---|
| Williamson County, IL | 1.71% | $5130 | $8550 |
| Illinois average | 1.83% | $5490 | $9150 |
| US national average | 1.10% | $3,300 | $5,500 |
Data sources: US Census Bureau ACS 5-Year Estimates, Tax Foundation, ATTOM Data Solutions
How Property Taxes Work in Williamson County
Williamson County, Illinois applies an effective property tax rate of 1.71% to assessed home values. This is above the national average of 1.10% and below the Illinois state average of 1.83%. On a home valued at the county median of $145600, a homeowner pays approximately $2490 per year — or $207.5 per month.
Property taxes in Illinois are administered at the county or municipal level. Rates reflect a millage rate applied to assessed value, which may be 50–100% of market value depending on local assessment practices. Many counties offer homestead exemptions, senior exemptions, disability exemptions, and veteran exemptions that can reduce the taxable assessed value — and therefore the effective rate shown above.
What Your Property Tax Funds
Property tax revenue in Williamson County funds local public schools, county government operations, road maintenance, emergency services (fire, EMS, police), parks, libraries, and other local services. The distribution among these uses varies by jurisdiction and year based on approved budgets and levies.
How to Appeal Your Assessment
If you believe your property is assessed above its fair market value, you can file an appeal with the Williamson County Assessor or Board of Review. Most jurisdictions have a formal appeals process with specific deadlines — typically 30–90 days after assessment notices are mailed. Successful appeals can meaningfully reduce your property tax bill for the current and future tax years.
Frequently Asked Questions
What is the property tax rate in Williamson County, Illinois?
The effective property tax rate in Williamson County is 1.71% of assessed home value. On the median home value of $145600, homeowners pay approximately $2490 per year. Your actual bill depends on your specific assessed value and any exemptions you qualify for.
How much are property taxes on a $400,000 home in Williamson County?
At the 1.71% effective rate, a $400,000 home in Williamson County would incur approximately $6840 per year in property taxes, or about $570 per month. Use the calculator above to estimate taxes for any home value.
How does Williamson County compare to the Illinois state average?
Williamson County's 1.71% effective rate is lower than the Illinois state average of 1.83%. Compared to the national average of 1.10%, it is above average.
Are there property tax exemptions available in Williamson County?
Most jurisdictions in Illinois offer homestead exemptions for primary residences, senior citizen exemptions for qualifying homeowners, disability exemptions, and veteran exemptions. These can reduce your assessed value and lower your effective tax rate below the area average. Contact the Williamson County Assessor's office to learn which exemptions you qualify for and how to apply.