City O'Fallon is a city in Illinois, in St. Clair County.
The median owner-occupied home in O'Fallon had a real-estate tax bill of $5,759 (± $257) a year, compared with $5,189 in Illinois and $2,969 nationwide. The median home value was $274,100 (± $10,520), compared with $250,500 in Illinois and $303,400 nationwide.
| Measure | O'Fallon | Illinois | United States |
|---|---|---|---|
| Population | 32,139 ± 38 | 12,692,653 | 332,387,540 |
| Median annual property tax bill (homeowners) | $5,759 ± $257 | $5,189 ± $19 | $2,969 ± $3 |
| Median home value | $274,100 ± $10,520 | $250,500 ± $863 | $303,400 ± $362 |
| Median household income | $102,793 ± $5,980 | $81,702 ± $363 | $78,538 ± $176 |
| Property tax as a share of home value (calculated) | 2.10% ± 0.12 points | 2.07% ± 0.01 points | 0.98% ± under 0.01 points |
| Homes lived in by their owners | 70.9% ± 2.3 points | 66.8% ± 0.3 points | 65.0% ± 0.3 points |
| Owner households headed by someone 65 or older | 27.3% ± 4.0 points | 31.3% ± 0.1 points | 32.6% ± 0.2 points |
| Owners spending 30% or more of income on housing costs | 15.5% ± 3.8 points | 22.1% ± 0.2 points | 22.2% ± 0.1 points |
How to read these numbers
- These are estimates from a survey, not a count. The American Community Survey asks a sample of households. The ± figure is the Census Bureau’s margin of error: the true value is very likely within that range of the estimate. Small places have large margins.
- “Too imprecise to report” means the margin of error is at least half of the estimate, so printing the number would suggest accuracy that does not exist. A “rough guide only” note means the margin is a quarter to a half of the estimate.
- Property tax bill and home value are medians for owner-occupied homes. Half of the homes are above the figure and half below. A median bill is not the rate set by a city or town; the bill combines taxes levied by every local government that serves the home, such as the school district and county.
- “Calculated” rows are worked out by Untax the Roof from the Census figures above them. They compare two medians, so they describe the place, not a particular household.
- Missing is not zero. Where the Census Bureau publishes no figure, this page says so.
Source: U.S. Census Bureau, American Community Survey 5-year estimates, 2019–2023: tables B25103 (real estate taxes), B25077 (home value), B19013 (household income), B01003 (population), B25003 (owners and renters), B25007 (age of householder), B25091 (housing costs as a share of income); see the Census ACS data page.
If property taxes go unpaid in Illinois
How it works. County tax sale of lien/certificate followed by circuit-court petition for tax deed
Excess sale money. Effective 2026 amendments create a surplus-equity fund. A former owner who loses property by issuance of a tax deed may seek an award based on property value less liens under 35 ILCS 200/21-302, subject to statutory rules
These rules are set by Illinois, not by O'Fallon, so this section is the same for every place in the state. Last verified 2026-09-25. See the full Illinois entry with statute links.