DeKalb County property tax appeal 2027: deadline, forms and how to file
To appeal a DeKalb County assessment, file with the DeKalb 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.
Assessment change notices are published and mailed together for all townships; for 2026 the publication date was September 10, 2026 for all 19 townships.
Data as of 20 Oct 2026 · DeKalb 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 DeKalb 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 DeKalb 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 |
|---|---|---|---|
| DeKalb County Residential Assessment Appeal Packet | — | Residential assessment complaint to the Board of Review (2026 edition) | |
| DeKalb County Commercial Assessment Appeal Packet | — | Commercial assessment complaint to the Board of Review (2026 edition) | |
| 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 | DeKalb 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 DeKalb 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.
DeKalb County questions
When is the DeKalb County appeal deadline for 2027?
No 2027 date is published yet. The board’s rule: Appeal form and all evidence must be received or postmarked within 30 calendar days of the publication date (2026: published September 10, deadline October 13, 2026, the same for every township). A 10-business-day extension to submit evidence (2026: to October 27) must be requested on the extension request form at the time the appeal is filed. Faxed or emailed appeal forms are not accepted.
How do I appeal my assessment in DeKalb County?
File the DeKalb County Residential Assessment Appeal Packet with the DeKalb County Board of Review, Administration Building, 110 E. Sycamore St., Sycamore, IL 60178. Mailed complaints count as filed on the postmark date.
Should I talk to the assessor first?
Yes. The township assessor or the DeKalb County Supervisor of Assessments can fix record errors informally. Still file with the DeKalb 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 DeKalb County Supervisor of Assessments (Chief County Assessment Office)?
Mail: DeKalb County Board of Review, Administration Building, 110 E. Sycamore St., Sycamore, IL 60178. Phone: 815-895-7120. Hours and walk-in details: dekalbcounty.org.
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
Kane County · Kendall County · Lee County · Boone County · Ogle County · McHenry County · DuPage County
- DeKalb County Assessment Office
- DeKalb County Board of Review
- DeKalb County Assessment Appeal
- DeKalb County Publications & Deadlines
- DeKalb County Board of Review Meetings
- DeKalb County Board of Review Rules (PDF)
- 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).