Lake County, IL: Property Taxes, Cross-Border Issues and CPA Help

Lake County is the northernmost of the Chicago-area counties we cover, running from Waukegan and North Chicago through Gurnee, Libertyville and Mundelein to the lakefront suburbs of Lake Forest and Highland Park. Its border with Wisconsin gives it a tax issue most Illinois counties do not have. This page explains Lake County property tax basics, the exemptions and appeals process, and the cross-border questions that come up for residents and employers.

Property tax cycle

Lake County follows the standard Illinois pattern: township assessors set values, the county assessment office reviews them, the Board of Review hears complaints, the County Clerk calculates rates and the Treasurer collects. The state's schedule gives Lake's assessors until July 15 to return their books. That puts assessment notices in mid-year and appeal windows in the late summer and fall.

For tax year 2025, the county's schedule put the installments in the first week of June and the first week of September (June 4 and September 4, 2026). Check your bill, because dates and penalty rules are set locally. Lake has also run a short December prepayment window, which for tax year 2025 ran from December 1 to 19 and capped prepayments at half of the prior year's tax. Prepaying can affect when you deduct the tax, so speak with us before you do it, and see our guide to the state and local tax deduction.

Exemptions

Because Lake borders Cook, the general homestead exemption can reduce assessed value by up to $8,000 for an owner-occupied home. Owners 65 and older can also claim a senior homestead exemption of up to $8,000. The senior assessment freeze has a household income limit that rises to $75,000 for the 2026 assessment year. Disability, disabled-veteran and returning-veteran exemptions are available as well. Apply through your township assessor; the Board of Review makes the final decision on homestead exemptions.

Appeals

Your township assessor should be your first call. The Board of Review then takes complaints in a short window after your township's roll is published, usually 30 days, and uses an online filing system. Rules about who may represent an owner at a Board of Review hearing vary by county, so ask the board before you hire anyone. A Board of Review decision can be appealed to the Property Tax Appeal Board within 30 days of the postmark.

Wisconsin next door

Many Lake County residents work in Wisconsin, and some Wisconsin residents work in Lake County. Each state may expect withholding and a return, and the state of residence usually allows a credit so the same wages are not taxed twice. A new job across the line, a relocation or remote work can change what each state expects, so ask us before you file. See our Wisconsin and multi-state payroll pages.

The community

About 27,800 Lake County residents, roughly 3.9%, identify as Asian Indian alone or in combination (American Community Survey, 2020 to 2024). We help families with cross-border finances, including FBAR reporting for Indian bank accounts and property in India.

How we can help

We work with Lake County clients remotely from Naperville. For homeowners, we can review exemptions and an assessment notice and tell you if an appeal looks worthwhile. For business owners, we prepare returns, set up payroll and sort out multi-state filings when employees or customers sit in Wisconsin. See our Chicagoland page for the wider area, and consult a qualified professional about your own situation.

Frequently asked questions

General information only, not tax, legal or accounting advice for your situation. Rules, limits and deadlines change; confirm the current rules with the official source or a qualified professional before you act. Reading this page does not create a professional relationship with CPA Tax Payroll and Accounting Corp.