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County tax profile · 2026 · Census ACS + IRS data

Property Tax & Income in Williamson County, Illinois

Williamson County has an effective property tax rate of 1.72%. On the median home value of $156,400, that's roughly $2,690 per year. Median household income is $65,604.

Effective Property Tax Rate1
1.72%
median tax $2,690 ÷ median home $156,400
Median Home Value1
$156,400
owner-occupied
Median Household Income1
$65,604
per-capita $37,284
Est. Annual Tax on Median Home1
$2,690
at 1.72% effective rate

What you'll pay, at a glance

Property taxes are the largest local tax most homeowners pay. The effective rate measures the real tax bill as a share of home value — a more useful number than the nominal “mill rate,” because assessment practices vary county to county.

MetricWilliamson CountyIllinois (state context)
Effective property tax rate11.72%1.80%
Median home value1$156,400—
State income tax3top rate 4.95%top rate 4.95%
State sales tax38.98% combined8.98% combined

How this is calculated

The effective property tax rate is the median real-estate tax bill divided by the median home value — both for owner-occupied homes, from the U.S. Census Bureau's American Community Survey (ACS 5-year estimates)1. Median income is also from the ACS1. Federal and state income-tax figures use IRS2 and Tax Foundation3 data.

About Williamson County, IL

Williamson County's effective property tax rate of 1.720% comes in just under Illinois's statewide median of 1.804%, though the gap is narrow enough that homeowners here won't feel much relief compared with the rest of the state. The county ranks 61st out of 102 Illinois counties, placing it squarely in the middle of the pack. Against the national median of 0.794%, however, the difference is stark — Williamson County property owners pay more than twice the national rate. That contrast says less about local spending choices than about Illinois's broader tax structure. On a median home value of $156,400, the annual tax bill reaches $2,690, set against a median household income of $65,604. Communities such as Cambria, Colp, and Freeman Spur sit within these same figures, and per-capita income of $37,284 helps explain why the tax load draws attention locally.

Frequently asked questions

What is the property tax rate in Williamson County, IL?
The effective rate is 1.72% — meaning the median tax bill equals about 1.72% of the median home value.
How much are property taxes on a median home?
On the median home ($156,400), the estimated annual bill is about $2,690.
Is Williamson County's rate high or low?
Compare it to the state median of 1.80% and the national average near 1.1%.
How does the effective rate differ from my mill rate?
A mill rate is the nominal levy per $1,000 of assessed value. The effective rate reflects what you actually pay after exemptions and assessments — it's the median tax bill as a share of median home value, so it better predicts your real cost.
Will a reassessment raise my tax bill?
Not necessarily. If your home's assessed value rises, your bill can go up, but only if the mill rate and exemptions stay flat. Contact the Williamson County assessor's office to review your current assessment.
Can I appeal my property tax assessment?
Yes. Most counties allow an appeal when you believe the assessed value exceeds the market value. File with the Williamson County assessor within the local deadline, typically with comparable sales as evidence.
Sources
[1] U.S. Census Bureau — ACS 5-Year (2023) — Median home value (B25077), median real-estate taxes (B25103), median household income (B19013), per-capita income (B19301).
[2] IRS — Statistics of Income — County income, AGI, and real-estate taxes paid.
[3] Tax Foundation — State income, sales, corporate, and estate/inheritance tax rates.