McHenry County property tax appeal 2027: deadline, forms and how to file
To appeal a McHenry County assessment, file with the McHenry County Board of Review online at www.mchenrycountyil.gov; 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.
Townships publish on different dates through the year. 2026 schedule: publications ran from July 7 (Richmond) through October 17, 2026 (Algonquin), with final filing deadlines from August 6 to November 16, 2026; a few townships (Dunham, Marengo, Riley) had no date posted as of 2026-10-20. The county also offers sign-up for notices when a township publishes.
Data as of 20 Oct 2026 · McHenry County Board of ReviewCheck your own assessment
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How to file in McHenry County
- Step 1
File the appeal
Online at www.mchenrycountyil.gov with the account number on your notice. State the grounds the county recognises.
- 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 McHenry 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 Comps 1 to 4 (grid) | — | Required comparables grid for residential complaints based on comparable sales or assessments (min. 3 comps) | |
| Residential Comps 5 to 9 (grid) | — | Additional residential comparables (up to 9 total) | |
| Commercial Grid Subject Comps 1 to 4 | — | Required grid for commercial complaints | |
| Commercial Grid Comps 5 to 9 | — | Additional commercial comparables if needed | |
| Industrial Grid Subject Comps 1 to 4 | — | Required grid for industrial complaints | |
| Industrial Grid Comps 5 to 9 | — | Additional industrial comparables if needed | |
| Authorization to Represent | — | Required when an agent/attorney files for the owner (original or secure digital signature); failure may result in dismissal | |
| Parcel Addendum Form | — | Only when more than one parcel is part of the complaint | |
| Vacancy Affidavit | — | Commercial/income-producing property with market-induced vacancy | |
| 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 | McHenry 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 McHenry 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.
McHenry County questions
When is the McHenry County appeal deadline for 2027?
No 2027 date is published yet. The board’s rule: Complaint must be filed within 30 days of the newspaper publication date for the property's township (late filings are not accepted). The county posts a township-by-township 'Township Filing Deadlines' table and an Assessment Progress / Board of Review Status Report. Complaints with appraisals: residential appraisals due within 20 calendar days after the filing deadline, commercial/industrial within 40 (2026 rules).
How do I appeal my assessment in McHenry County?
File online at mchenrycountyil.gov. Online filing is the method the McHenry County Board of Review publishes.
Should I talk to the assessor first?
Yes. The township assessor or the McHenry County Supervisor of Assessments can fix record errors informally. Still file with the McHenry 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 McHenry County Office of Assessments (Supervisor of Assessments / Chief County Assessment Officer)?
Mail: McHenry County Board of Review, 2200 N Seminary Ave, Administration Building Rm 106, Woodstock, IL 60098 (hearings at 667 Ware Rd, Suite 106, Woodstock). Phone: 815-334-4290. Hours and walk-in details: mchenrycountyil.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 · Kane County · DeKalb County · Lake County · Winnebago County · DuPage County · Ogle County
- McHenry County Filing A Complaint
- McHenry County 2026 Township Filing Deadlines
- McHenry County Board of Review
- McHenry County Assessments
- McHenry County 2026 Board of Review Rules (PDF, effective 6/1/2026)
- 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).