Grundy County property tax appeal 2027: deadline, forms and how to file
To appeal a Grundy County assessment, file with the Grundy 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.
Per the 2026 BOR rules, the Chief County Assessment Officer publishes the assessment roll in late summer to early fall. For 2026, assessment notices were dated and published September 23, 2026 (mailed by USPS and published in the Coal City Courant and the Morris Herald-News). Starting with 2026, parcels changed only by the equalization factor or state farmland values are not mailed individual notices.
Data as of 20 Oct 2026 · Grundy 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 Grundy 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 Grundy 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 |
|---|---|---|---|
| Grundy County Real Estate Assessment Complaint Form (Assessment Year 2026) | — | Required BOR complaint form; one form per parcel, with evidence | Fillable PDF |
| Board of Review Limited Power of Attorney | — | Owner authorization when an attorney files on the owner's behalf | |
| 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 | Grundy 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 Grundy 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.
Grundy County questions
When is the Grundy County appeal deadline for 2027?
No 2027 date is published yet. The board’s rule: One county-wide deadline is posted each year (30 days after publication of the roll). For 2026 the deadline was Monday, October 26, 2026 at 4:30 p.m.: in person must be received by 4:30 p.m.; email (bor@grundycountyil.gov) by 11:59 p.m. with the signed form and all evidence; mail postmarked by 11:59 p.m. A metered-mail date is not accepted as a postmark. The 2027 date had not been published.
How do I appeal my assessment in Grundy County?
File the Grundy County Real Estate Assessment Complaint Form (Assessment Year 2026) with the Grundy County Board of Review, c/o Supervisor of Assessments, Grundy County Courthouse, 111 E. Washington St., Morris, IL 60450. Mailed complaints count as filed on the postmark date.
Should I talk to the assessor first?
Yes. The township assessor or the Grundy County Supervisor of Assessments can fix record errors informally. Still file with the Grundy 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 Grundy County Supervisor of Assessments?
Mail: Grundy County Board of Review, c/o Supervisor of Assessments, Grundy County Courthouse, 111 E. Washington St., Morris, IL 60450. Phone: 815-941-3269. Hours and walk-in details: grundycountyil.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
Kendall County · Will County · LaSalle County · Livingston County · Kankakee County · DuPage County · Kane County
- Grundy County Board of Review
- Grundy County Supervisor of Assessments
- Grundy County 2026 Board of Review Rules & Procedures (PDF)
- Grundy County Real Estate Assessment Complaint Form 2026 (PDF)
- 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).