Winnebago County property tax appeal 2027: deadline, forms and how to file
To appeal a Winnebago County assessment, file with the Winnebago County Board of Review by mail 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.
For tax year 2026 the county posted assessments online July 31 (5:00 PM), mailed notices August 3, and published August 5 (Cherry Valley, Durand, Laona, Owen, Rockford) or August 6 (Burritt, Harlem, Harrison, Pecatonica, Rockton, Roscoe, Seward, Shirland, Winnebago townships).
Data as of 20 Oct 2026 · Winnebago 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 Winnebago 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 Winnebago 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 |
|---|---|---|---|
| 2026 Board of Review Rules and Procedures | — | Board of Review rules of procedure | |
| Comparable-Property Grid Sheet (Residential) | — | Optional grid for listing comparable properties | |
| Comparable-Property Grid Sheet (Commercial/Industrial) | — | Optional grid for listing comparable properties on commercial/industrial parcels | |
| 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 | Winnebago 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 Winnebago 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.
Winnebago County questions
When is the Winnebago County appeal deadline for 2027?
No 2027 date is published yet. The board’s rule: The Board of Review publishes a complaint deadline by township group each year, 30 calendar days after publication (2026: September 4 or 5). Complaints must be on the county's Real Estate Assessment Complaint Form; late complaints are returned and not considered; faxed or emailed complaints are not accepted. Rules call for the original plus one copy of the form and of all written evidence.
How do I appeal my assessment in Winnebago County?
File a written complaint on the board’s form with the Winnebago County Board of Review, 404 Elm Street, Room 301, Rockford, IL 61101. Mailed complaints count as filed on the postmark date.
Should I talk to the assessor first?
Yes. The township assessor or the Winnebago County Supervisor of Assessments can fix record errors informally. Still file with the Winnebago 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 Winnebago County Supervisor of Assessments?
Mail: Winnebago County Board of Review, 404 Elm Street, Room 301, Rockford, IL 61101. Phone: 815-319-4463. Hours and walk-in details: wincoil.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
Boone County · Ogle County · Stephenson County · McHenry County · DeKalb County · Lee County · Carroll County
- Winnebago County - Board of Review
- Winnebago County - Supervisor of Assessments
- Winnebago County - Publication list
- Winnebago County - 2026 Board of Review Rules and Procedures
- 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).