Boone County property tax appeal 2027: deadline, forms and how to file
To appeal a Boone County assessment, file with the Boone 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.
The Board of Review sits after the township assessors and the Assessment Office publish assessment changes; publication lists are posted by year on the Assessment Office's Publication Lists page. The 2027 publication date is not yet published.
Data as of 20 Oct 2026 · Boone 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.
By checking an address you agree to the Terms and Privacy Policy. We keep an address only if you add it to a dashboard; we never sell it.
How to file in Boone 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 Boone 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 Residential/Farm Assessment Complaint | — | Required complaint form for residential and farm property | |
| 2026 Commercial/Industrial Assessment Complaint | — | Required complaint form for commercial and industrial 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 | Boone 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 Boone 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.
Boone County questions
When is the Boone County appeal deadline for 2027?
No 2027 date is published yet. The board’s rule: Appeals must be filed on or before 30 days after publication of the current-year assessments (35 ILCS 200/16-55); the Board posts the filing date on the county website. The Board accepts official postmarks, hand delivery to the Supervisor of Assessments Office, and e-mail submissions to BOR@boonecountyil.gov on or before the deadline; faxes are not accepted.
How do I appeal my assessment in Boone County?
File the 2026 Residential/Farm Assessment Complaint with the Boone County Board of Review, 1212 Logan Avenue, Suite 101, Belvidere, IL 61008. Mailed complaints count as filed on the postmark date.
Should I talk to the assessor first?
Yes. The township assessor or the Boone County Supervisor of Assessments can fix record errors informally. Still file with the Boone 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 Boone County Supervisor of Assessments (Assessment Office)?
Mail: Boone County Board of Review, 1212 Logan Avenue, Suite 101, Belvidere, IL 61008. Phone: 815-544-2958. Hours and walk-in details: boonecountyil.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
Winnebago County · McHenry County · DeKalb County · Ogle County · Kane County · Stephenson County · Lee County
- Boone County Board of Review
- Boone County Assessment Office
- 2026 Boone County Board of Review Rules (PDF)
- 2026 Residential/Farm Assessment Complaint (PDF)
- Boone County Assessment Office Publication Lists
- 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).