How to Appeal Property Taxes in St. Louis County, Missouri (2026 Guide)

The 2026 St. Louis County Board of Equalization appeal deadline was Monday, July 13, 2026—the second Monday in July. As of July 23, 2026, the regular 2026 filing window is closed; the next regular county deadline is expected to be Monday, July 12, 2027, unless the Board extends it.

File with the St. Louis County Board of Equalization (BOE) through the county’s online BOE filing page, or by paper form delivered/postmarked to Board of Equalization, 41 S Central Ave, Clayton, MO 63105. Online filing is the county’s preferred method; the county does not list a BOE filing fee for a residential assessment appeal.

How assessments work in St. Louis County

St. Louis County’s Assessor values real estate for tax purposes countywide. The county’s own budget materials describe roughly 400,000 residential and commercial real estate parcels, and Missouri law requires real estate reassessment every two years in odd-numbered calendar years. That means 2025 was the most recent countywide reassessment year and 2026 is a non-reassessment year unless your property changed significantly—new construction, demolition, major physical change, or another reason the Assessor updates the record.

For a normal reassessment, the value question is: what was the property’s fair market value on January 1 of the reassessment year? For 2025/2026 values, the key date is January 1, 2025. The county’s appeal instructions define fair market value as what the property would sell for on the open market as of that date—not what you owe on the mortgage and not what you wish taxes were.

Missouri uses assessment ratios. For owner-occupied or other residential real estate, the taxable assessed value is generally 19% of true market value. Example: a $300,000 residential appraised value becomes $57,000 assessed value before tax rates are applied.

St. Louis County sends Change of Assessment Notices in the spring of reassessment years. Residential notices are mailed in May; commercial notices later in May or early June. In even-numbered years, some owners may still receive a notice if the property’s physical characteristics changed.

Local inspection rules matter. County budget materials say appraisers physically inspect every residential property whose value increases by more than 15% from the prior reassessment, every parcel gets a physical inspection at least once every six years, and owners may request a reinspection.

Whether you should appeal

Appeal if you can show the Assessor’s market value is too high, the property is classified incorrectly, or your property is assessed at a worse ratio than comparable properties. St. Louis County’s paper instructions list exactly those three reasons: Property Value, Property Classification, and Ratio.

For most homeowners, the strongest appeal is a market-value appeal. Good evidence includes:

• a recent arm’s-length purchase of your home near January 1, 2025;
• comparable sales from your neighborhood, subdivision, school district, or municipality;
• photos of condition problems the Assessor may not know about;
• contractor estimates for needed repairs that existed as of the valuation date;
• an appraisal that uses the relevant valuation date; and
• evidence that the county record is wrong—finished basement counted when unfinished, wrong square footage, extra bath, garage error, etc.

Do not rely on “my taxes are too high” by itself. The BOE is deciding value/classification/ratio, not whether school or municipal levies are too expensive.

St. Louis County does not appear to publish an official residential appeal success rate or median reduction in the county materials reviewed. What the county does publish is scale: for the 2025 reassessment year, budget materials anticipated about 27,000 appeals of all types and funded additional BOE capacity, including a third Board of Equalization and more hearing-officer days.

Step-by-step how to file

1. Find your locator number. For real estate, use the locator number shown on your Change of Assessment Notice, prior tax bill, or St. Louis County real estate search. You need a separate appeal for each locator number.

2. Use the correct form. For homeowners, the key county form is the 2026 Property Assessment Appeal Form. The county also publishes Board of Equalization Property Assessment Paper Appeal Form (and Instructions). If someone represents you, the BOE Representative Authorization Form is required at filing and must be signed by the owner. The BOE page also lists supplemental forms for personal property and business/manufacturer appeals, but a typical homeowner real-estate appeal usually starts with the main Property Assessment Appeal Form.

3. Choose your hearing method. The 2026 form offers three practical choices: waive your appearance and have the BOE decide on documents and written statements; appear by video conference; or appear by telephone. The form states 2026 hearings are by video or telephone conference only.

4. State your opinion of value. Do not leave this blank. Put the dollar amount you believe the home would have sold for on the open market as of January 1 of the reassessment year. If the county says $360,000 and your evidence supports $325,000, write $325,000.

5. Attach evidence before the deadline. St. Louis County says all forms and supporting documents—appraisals, repair estimates, photos, sales contracts, and similar evidence—must be filed on or before the second Monday in July to be considered. The county encourages submitting evidence at the same time as the appeal.

6. File. The methods shown in county materials are:

• Online portal: file through the BOE page at stlouiscountymo.gov/boe; this is the county’s preferred method and gives faster processing.
• Mail: paper forms must be postmarked by the deadline to Board of Equalization, 41 S Central Ave, Clayton, MO 63105.
• In person/drop box: deliver to the same address, 41 S Central Ave, Clayton, MO 63105.
• Email for follow-up evidence/questions: the county’s online filing page lists boe@stlouiscountymo.gov for questions and says evidence not submitted at online filing may be submitted by email, mail, or delivery by the second Monday in July. Because the paper instructions emphasize online filing or postmark/delivery for paper appeals, do not assume an emailed form alone is enough unless BOE staff confirms.

What happens after

The proper appeal authority is the St. Louis County Board of Equalization. The Boards are independent bodies; county budget materials state their members are appointed by the County Executive, approved by the County Council, and report to the Director of Revenue.

After filing, you receive a hearing notice by email or U.S. Mail to the owner’s address of record or alternate address you provided. If you chose a video or telephone hearing, expect a short, evidence-focused session. Be ready to explain your opinion of value and point to the exact documents that support it. If you waive appearance, the BOE should decide from your written evidence; the county form says the Board will not prejudice the appeal for non-attendance and will notify you of its decision.

County materials do not promise a fixed number of days for a BOE decision. If you disagree with the BOE result, the next appeal is to the Missouri State Tax Commission. The STC deadline is September 30 of the assessment year or 30 days after the BOE decision, whichever is later. For ordinary real estate, you usually must go through the BOE first.

Local tips

Use St. Louis County’s own tax math. The county’s 2025 adopted residential county tax rate is $0.379 per $100 of assessed value for all county funds. A $25,000 reduction in residential market value lowers assessed value by $4,750 ($25,000 × 19%). At the county-only rate, that saves about $18.00 per year ($4,750 ÷ 100 × $0.379). Your total bill savings will usually be much larger because your bill also includes school district, municipality, fire/service districts, library and other levies; use your prior tax bill’s total rate for a full estimate.

Check relief programs even if you miss the appeal. St. Louis County’s Senior Property Tax Freeze is separate from a valuation appeal and can matter more long-term for qualifying seniors. Missouri’s Property Tax Credit, often called the circuit breaker, may help certain seniors and 100% disabled individuals; the state lists a maximum credit of $1,100 for qualifying owners who owned and occupied their home. For veterans, St. Louis County’s FAQ says Missouri currently allows real-property tax relief only for former POWs who became 100% disabled due to service, using the county’s disabled POW real property tax exemption application.

If the 2026 deadline passed, preserve your file. Keep your comps, photos, estimates, and appraisal notes. If your 2027 notice changes again, you will be ready to file early in the May 1–second-Monday-in-July window.