Will County Property Tax, Assumed Business Name and Permit Guide

Will County lies south of DuPage and Kane counties and includes Joliet, Plainfield, Bolingbrook and parts of Naperville and Aurora. If you own or rent out a home in one of those towns, or you are starting a company in the county, you will use the same handful of county offices. This guide covers Will County property tax, how its calendar differs from neighboring counties, how to file an assumed business name, and which permits the county itself issues.

Who does what in Will County government?

Will County has a County Executive office, so that title appears on licensing pages alongside the County Board.

What is the Will County property tax calendar?

Like the rest of Illinois, the tax is billed one year behind. The Treasurer's published levy calendar for the 2025 tax year payable in 2026 looks like this:

Interest on a late first installment is 1.5% per month, stepping up to 3%, 4.5% and 6% as months pass. If you buy after bills are mailed, the Treasurer sends bills beginning in June to owners whose deeds were recorded after May 1. Not receiving a bill never cancels the liability, and the office tells owners to request a duplicate.

The Treasurer does not report late payment to credit agencies. Bank collection sites pause from June 1 to August 1 and stop for the year after September 1, so check where you can pay before the deadline.

How do exemptions and appeals work in Will County?

Homestead exemptions go through the Supervisor of Assessments or directly through your township assessor. The office lists the senior citizen homestead exemption (age 65, primary residence, state form PTAX-324) and the low-income senior assessment freeze. For 2026 it states an income limit of $75,000 and mailed renewal applications on April 10, 2026, so confirm eligibility with the office before relying on a figure.

The senior freeze caps the assessed value, not the tax rate, so a bill can still rise if the district rate rises.

To contest a valuation:

1. Review the property record and compare similar parcels.
2. Talk to your township assessor.
3. File with the Board of Review when your township's complaint period opens; the Supervisor's office notes that the period begins in August.
4. If you hire an attorney, note that from 2026 the attorney must attach a notarized authorization from an owner of record.

Property damaged in the disaster covered by the August 18 gubernatorial proclamation can use form PTAX-245 with the assessor.

How do you register an assumed business name in Will County?

State law (805 ILCS 405) requires individuals who do business under a name other than their own to file a certificate with the County Clerk. LLCs, LLPs and corporations register with the Secretary of State instead.

1. Complete the Certificate of Registration of Ownership of Business.
2. File it with the $10 fee at the Will County Clerk's office, in person or by mail.
3. Publish the certificate in a Will County newspaper of general circulation within 15 days of filing.
4. Submit the newspaper's Certificate of Publication within 50 days of filing.
5. Receive the Certificate of Ownership and Receipt of Publication.

You cannot change the business name itself; you register a new one. Changes of address, owner name or an added owner use a Certificate of Change and Addition, and withdrawing a name costs $1.50 with publication only when 25% or more of ownership is withdrawn. The Clerk posts a monthly list of initial registrations, but a listing does not prove that publication is complete. Our assumed name guide shows how this compares with an LLC.

Which county permits and licenses might you need?

• Building: the Land Use Department's Development Services Division runs a cloud-based portal for permit applications, documents, inspections and fees. Plan review fees for new residential and for industrial or commercial projects are set by a third-party review company.
• Food: a proposal must be submitted to the Health Department's Division of Environmental Health before you build or remodel a food service. Initial plan review generally takes 10 to 14 days, an expedited review at twice the fee takes about 7 days, and a pre-opening inspection is required before a permit is issued.
• Liquor and transportation: the County Executive licenses liquor in unincorporated areas; the Division of Transportation issues access, utility and oversize vehicle permits.

Inside Joliet, Plainfield, Bolingbrook or Naperville, the municipality is your first stop; see the local licenses, permits and zoning guide.

What sales tax rates apply?

The state's rate file shows the Will County row at 7.25% for general merchandise from August 1, 2026, after the regional transit increase announced in Illinois Department of Revenue bulletin FY 2026-34. Municipalities add to it: Naperville 8.00%, Oswego 8.50%, Plainfield and Bolingbrook 8.75%. Joliet's base rate is 9.00% with address-specific exceptions. See the Illinois sales and use tax guide.

Where can you get help?

The Illinois SBDC network lists centers at Waubonsee Community College and College of DuPage near the county. The county's economic development link points to the Will County Center for Economic Development, and the Joliet Arsenal Enterprise Zone, created in 2002, targets the former arsenal area. Read the small business resources guide.

Main municipalities in our local guides

• Joliet, the county seat
• Plainfield and Bolingbrook
• Naperville and Aurora, whose southern sections are in Will County
• Oswego, partly in Will County

A quick example

Ravi owns a rental townhome in Bolingbrook with a $9,600 annual bill. Each installment is $4,800. If he pays the second one a month late, interest at 1.5% adds $72. He also saves the receipt because the Treasurer applies partial payments and prepayments to the parcel number, so he writes the PIN on every check.

Mistakes to avoid

• Writing a check without the parcel number.
• Assuming the mortgage lender will always pay; duplicate payments need a refund affidavit.
• Waiting for November 30 to correct a missed installment.
• Registering a trade name after you have already printed marketing under it.

How we can help

Our firm, based in the Aurora and Fox Valley area, helps Will County owners with U.S. returns, rental property reporting, Illinois registrations, sales tax and payroll. Where income or property sits in India or Canada, we coordinate with your Canadian CPA or Indian Chartered Accountant. See real estate investor tax and business formation and registrations.

Frequently asked questions

General information only. It is not tax, legal, accounting or immigration advice for your situation, and rules change; confirm the current rules with the official source or a licensed professional in the relevant country.