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St. Louis County at a glance
Population: 987,059 (Census estimate, 2023) — the 1st largest of 115 Missouri counties and county equivalents.
Typical tax bill: $3,101 a year (median for owner-occupied homes, ACS 2022 5-year estimate) — the Missouri median is $1,812.
Land area: 508 sq mi, about 1,943 people per sq mi.
If you pay late
Late charges accrue on the unpaid balance at up to 18% interest per year plus a 2% penalty.
Calendar tax year; bills for each year are issued ahead of the December 31 payment deadline. If a due date lands on a weekend or public holiday, most counties move it to the next business day — check the county's own notice before relying on the shift.
By post: mail a cheque to the treasurer's office; the postmark date usually counts, not the arrival date.
In person: the treasurer's office during business hours; bring your bill or parcel number.
Mortgage escrow: if your taxes are escrowed, the servicer pays — you still owe the difference if your escrow is short.
Common questions
When are property taxes due in St. Louis County, MO?
Full year: December 31, 2026.
What happens if I pay late in St. Louis County?
Late charges accrue on the unpaid balance at up to 18% interest per year plus a 2% penalty.
How do I pay St. Louis County property tax?
Pay online through taxpayments.stlouiscountymo.gov, the county's own payment portal, or by post or in person at the treasurer's office.
Is the St. Louis County deadline the same every year?
Calendar tax year; bills for each year are issued ahead of the December 31 payment deadline. Counties shift dates when billing is delayed, so confirm against the county source linked on this page.
What if I can't pay in full?
Most counties offer instalment plans or partial payment — ask the treasurer before the due date, not after. Once the bill is delinquent the options shrink and the fees start.
Does a late payment affect my mortgage?
Unpaid property tax is a lien on the property in most states, which your servicer may pay and then bill you for, with fees. It does not disappear.
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CountyTaxDates is an independent reference and is not a government agency. Deadlines change and exceptions apply — always confirm with your county treasurer using the official link on this page. Nothing here is tax, legal or financial advice.