Knox County property tax appeal 2027: deadline, forms and how to file
To appeal a Knox County assessment, file with the Knox County Board of Review by mail, by email or in person; in Illinois the deadline is 30 days after the township assessment list is published (Cook County uses township filing windows). Confirm the exact date on your notice or with the assessor; we add each county's 2027 date here when it is published.
Knox County publishes one county-wide assessment change list each year; for 2026 the Board of Review appeal window ran September 17 to October 19, 2026 (30 days from publication).
Data as of 20 Oct 2026 · Knox County Board of ReviewCheck your own assessment
Free. We compare the value on your notice with recent sales of similar homes nearby and tell you whether an appeal is worth filing. Have your assessment notice and tax bill handy.
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How to file in Knox County
- Step 1
File the appeal
Use the method your notice lists, by the deadline on the notice.
- Step 2 · before the hearing
Prepare and submit your evidence
Overvaluation must be shown by a preponderance of the evidence; a uniformity (equity) claim needs clear and convincing evidence. The strongest evidence is a recent arm’s-length purchase of your home, or an appraisal as of January 1. Otherwise use at least three comparable sales, or for equity at least three similar nearby homes with their assessments and property record cards, in a grid. Bring a photo of your home and its property record card.
- Step 3
Meet, then hear
An informal review with Township assessor or Supervisor of Assessments comes first; if you decline the offer, the Knox County Board of Review hears the case. Most reductions happen at the first step.
Before you file: how to read your notice · evidence that works · informal vs formal hearing · when not to appeal
Forms
| Form | Number | Use | Format |
|---|---|---|---|
| Residential Appeal Form (2026) | — | Board of Review complaint for residential property | |
| Commercial or Industrial Appeal Form (2026) | — | Board of Review complaint for commercial or industrial property | |
| Farm Appeal Form (2026) | — | Board of Review complaint for farm property | |
| Residential Appeal (Property Tax Appeal Board) | PTAB-1A | Only after the Board of Review decides: the state appeal, due 30 days after the board’s written notice. Can also be filed online through PTAB eFile. | Fillable PDF |
Appeal levels
| Level | Who hears it | Deadline | Cost |
|---|---|---|---|
| Informal review | Township assessor or Supervisor of Assessments | Before the Board of Review deadline | Free |
| Board of Review | Knox County Board of Review | 30 days after the assessment list is published | Free |
| Property Tax Appeal Board | Illinois Property Tax Appeal Board (state) | 30 days after the Board of Review’s written decision | No filing fee |
| Court | Circuit court (administrative review), or a tax objection in Knox County circuit court | 35 days after the PTAB decision; tax objections follow the tax-bill penalty date | Court costs |
What evidence the board accepts
Overvaluation must be shown by a preponderance of the evidence; a uniformity (equity) claim needs clear and convincing evidence. The strongest evidence is a recent arm’s-length purchase of your home, or an appraisal as of January 1. Otherwise use at least three comparable sales, or for equity at least three similar nearby homes with their assessments and property record cards, in a grid. Bring a photo of your home and its property record card.
Knox County questions
When is the Knox County appeal deadline for 2027?
No 2027 date is published yet. The board’s rule: Complaints must be filed within 30 days after publication of the township assessment roll; the county posts one county-wide deadline each year (4 p.m. on October 19 in 2026, for drop-offs, postmarks and emailed appeals). Mail is filed on the USPS postmark date (metered mail needs the USPS date stamp), hand deliveries on the date received, and emailed appeals must show a time stamp of 4 p.m. or earlier. Late complaints are returned and not considered. One set of the complaint form and one set of all evidence must be submitted.
How do I appeal my assessment in Knox County?
File the Residential Appeal Form (2026) with the Knox County Board of Review, 121 S. Prairie St., Suite 1, Galesburg, IL 61401. Mailed complaints count as filed on the postmark date.
Should I talk to the assessor first?
Yes. The township assessor or the Knox County Supervisor of Assessments can fix record errors informally. Still file with the Knox County Board of Review by the deadline: a board complaint is required before any state appeal.
What evidence works best?
A recent arm’s-length purchase of your home or an appraisal as of January 1. Otherwise, at least three comparable sales, or three similar nearby homes with lower assessments, with property record cards and photos.
How do I contact the Knox County Supervisor of Assessments (Assessment Office)?
Mail: Knox County Board of Review, 121 S. Prairie St., Suite 1, Galesburg, IL 61401. Phone: 309-345-3845. Hours and walk-in details: knoxcountyil.gov.
What if the Board of Review says no?
Appeal to the Illinois Property Tax Appeal Board within 30 days of the board’s written decision. There is no fee, and you can file online through PTAB eFile. A lowered value on an owner-occupied home carries over for the rest of the assessment period.
Check whether yours is over-assessed
Nearby counties
Warren County · Stark County · Peoria County · Henry County · Fulton County · Mercer County · Henderson County
- Knox County Board of Review Appeals page
- Knox County Assessment Changes (2026 notice, deadline and equalization factors)
- Knox County Assessment Office
- Knox County Board of Review contact page
- Knox County Board of Review 2026 Rules (DOCX)
- Knox County 2026 Residential Appeal Form
- Illinois State Board of Elections County Officers directory
- 35 ILCS 200/16-55 — Board of Review complaints
- 35 ILCS 200/12-10 — Publication of assessments
- 35 ILCS 200/16-160 — Appeal to the Property Tax Appeal Board
- Illinois DOR — Assessment Appeals
- Property Tax Appeal Board — Filing your appeal
- Property Tax Appeal Board — FAQ
- U.S. Census Bureau, county population estimates (2024) and county gazetteer (2024).