Lake County, IL

Lake County property tax appeal 2027: deadline, forms and how to file

Scan from recent salesFacts not yet verified by a person — confirm on your notice

To appeal a Lake County assessment, file with the Lake County Board of Review online at lakecountyilpaefile.tylertech.com; 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 Chief County Assessment Office publishes assessment changes township by township; for 2026 it anticipated publication starting mid-to-late July, and the published 2026 schedule runs from 7/23/2026 (Benton, Ela) to 10/1/2026 (Shields).

Data as of 20 Oct 2026 · Lake County Board of Review

Your home

Check 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

How to file in Lake County

Step 1
File the appeal
Online at lakecountyilpaefile.tylertech.com 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 Lake 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

Forms accepted by Lake County Board of Review, 2027
Form	Number	Use	Format
Residential Appeal (SmartFile e-filing application)	—	Residential assessment appeal filed electronically with the Board of Review (create an account first)	Online
Commercial/Industrial Appeal (SmartFile e-filing application)	—	Commercial and industrial assessment appeal filed electronically	Online
Board of Review Vacancy Affidavit	—	Supporting affidavit for vacancy-based appeals of income-producing commercial property	PDF
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

Levels

Appeal levels

Where a Lake County protest can go, in order
Level	Who hears it	Deadline	Cost
Informal review	Township assessor or Supervisor of Assessments	Before the Board of Review deadline	Free
Board of Review	Lake 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 Lake County circuit court	35 days after the PTAB decision; tax objections follow the tax-bill penalty date	Court costs

Evidence

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.

Questions

Lake County questions

When is the Lake County appeal deadline for 2027?

No 2027 date is published yet. The board’s rule: Appeals must be filed within 30 days after the date the township's assessments are published; the filing deadline for each property is printed on its assessment notice. The county posts a township-by-township table of publication dates and final filing dates each year (2026 filing dates ranged 8/24/2026 to 11/2/2026). The Board says deadlines are fixed and are not extended if the online application is unavailable, and recommends not waiting until the last day.

How do I appeal my assessment in Lake County?

File online at lakecountyilpaefile.tylertech.com. Online filing is the method the Lake County Board of Review publishes.

Should I talk to the assessor first?

Yes. The township assessor or the Lake County Supervisor of Assessments can fix record errors informally. Still file with the Lake 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 Lake County Chief County Assessment Office?

Mail: Lake County Board of Review, 18 N. County Street, 7th Floor, Waukegan, IL 60085. Phone: 847-377-2100. Hours and walk-in details: lakecountyil.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.

Your home

Check whether yours is over-assessed

Nearby

Nearby counties

Cook County · DuPage County · McHenry County · Kane County · Will County · Kendall County · Boone County

Sources