What Illinois Home Sellers Must Disclose in 2026: A DuPage County Guide

By John Salidas, Broker | The Salidas Group at @properties Christie's International Real Estate | Research checked October 19, 2026

If you are preparing to sell a house, condominium or townhome in Elmhurst, Glen Ellyn, Wheaton, Lombard, Naperville or elsewhere in DuPage County, disclosure paperwork should begin before the listing goes live. Illinois law generally requires a seller to give a prospective buyer a completed Residential Real Property Disclosure Report before the buyer signs a contract. Separate Illinois radon paperwork and federal lead-based paint rules may also apply.

The practical goal is not to diagnose the property yourself or predict every future repair. It is to answer the required forms accurately from your actual knowledge, deliver them at the correct time and update them if relevant information changes before closing. This guide is general educational information, not legal advice. Your Illinois real estate attorney should advise you on the facts of your transaction.

The core Illinois rule: disclose known material defects before contract

The Illinois Residential Real Property Disclosure Act applies to many transfers of residential real property. Section 20 requires the seller to complete the statutory report and deliver it to the prospective buyer before the signing of a contract.

The statutory form defines a material defect as a condition that would substantially reduce the property's value or significantly impair the health or safety of future occupants, unless the seller reasonably believes the condition has been corrected. The form is based on the seller's actual notice or actual knowledge. The Act does not require the seller to conduct a new investigation simply to complete the report.

That distinction matters. A seller should not guess, minimize or conceal a known issue, but the disclosure report is not a substitute for a professional home inspection. Buyers still need their own due diligence, and sellers should not make technical conclusions outside their expertise.

What the Illinois disclosure report covers

The current statutory disclosure form asks about the seller's occupancy and flood insurance, then addresses known conditions involving flooding or recurring leakage, floodplain location, the basement or foundation, the roof, ceilings or chimney, and major building systems. It also covers additional property conditions listed in the official form.

A 'yes' answer is not automatically a reason a home cannot be sold. It is a signal that the explanation and supporting records should be organized. A documented repair can be easier for a buyer to evaluate than a vague answer discovered later during inspection.

Do not treat the form as a memory exercise completed on the morning of listing. Review old invoices, permits, insurance claims, warranties, inspection reports, environmental tests and mitigation records. If you are unsure how a prior event should be characterized, raise it with your attorney before the form is delivered.

Delivery timing and the duty to supplement

Illinois law says the report should be delivered before contract signing. If a report disclosing a material defect is delivered after all parties signed, Section 40 describes circumstances in which the buyer may have a five-business-day termination right.

The obligation does not necessarily end when the first form is signed. Under Section 30, if the seller becomes aware before closing of an error, inaccuracy or omission in an earlier report or supplement, the seller must provide a written supplemental disclosure.

A simple example is a new roof leak that appears after contract but before closing. Another is receiving a contractor's report that changes what the seller understands about a foundation crack. The correct response is not to wait and hope the issue remains unnoticed. Notify your broker and attorney promptly so the contract, disclosure and repair strategy can be handled together.

Three common DuPage County examples

1. Basement seepage or drainage history

Older and newer homes can experience seepage for different reasons, including grading, gutters, foundation openings, sump systems or heavy rain. If a Wheaton or Glen Ellyn seller previously had recurring water and later installed drainage improvements, gather the invoices, transferable warranties and any follow-up documentation. Whether and how that history must be stated on the form depends on the facts and the legal wording. Do not assume that a repair automatically makes the history irrelevant.

2. A roof or chimney leak that was repaired

Suppose an Elmhurst seller had a flashing leak, hired a roofer and has had no recurrence. Keep the roofer's scope, date, invoice and warranty. Clear documentation helps the buyer and inspector understand what occurred. It also helps the seller answer follow-up questions consistently instead of relying on a vague recollection.

3. A radon test and mitigation system

If a Naperville, Lombard or other Illinois property has a prior radon test showing an elevated result, or a mitigation system was installed, keep the test reports, mitigation records and service information. Illinois radon paperwork is separate from the general property disclosure report.

Illinois radon disclosures are separate

The Illinois Radon Awareness Act generally requires a seller to provide the buyer with the IEMA-OHS radon pamphlet and the Illinois Disclosure of Information on Radon Hazards before the buyer is obligated under a purchase contract. The statute does not itself require the seller to perform a radon test or mitigation.

The seller must provide information in the seller's possession about radon test results showing elevated levels. IEMA-OHS provides the approved real estate radon guidance and disclosure resources and strongly recommends that buyers test before purchase or occupancy.

A mitigation system should not be treated as a stigma. It is a property feature that buyers can evaluate through records, current testing and professional review. The key is accurate documentation and an orderly handoff.

Federal lead-based paint rules for most pre-1978 housing

For most housing built before 1978, the federal Lead-Based Paint Disclosure Rule requires sellers and their agents to provide specific information before the buyer signs the contract.

The seller must disclose known information about lead-based paint and lead hazards, provide available records and reports, give the buyer the federal lead pamphlet, and include the required warning and acknowledgments. Buyers generally receive a 10-day opportunity to conduct a lead inspection or risk assessment, although the parties can change that period in writing or the buyer can waive it. The EPA also says signed disclosure records should be retained for three years after the sale.

These federal rules are about known information and required notices. They do not mean every pre-1978 home contains a known lead hazard, and they do not replace a buyer's decision about testing.

Are any Illinois transfers exempt?

Some transfers are exempt from the Illinois Residential Real Property Disclosure Act, including categories of court-ordered, estate, foreclosure, fiduciary and other transfers listed in Section 15. Exemption analysis can be fact-specific. A seller should not assume that an estate, trust, relocation or family transaction is exempt simply because it feels unusual. Ask the closing attorney to confirm which state and federal forms still apply.

What sellers should assemble before listing

Start a digital property file with repair invoices, warranties, permits, contractor scopes, insurance-claim records, environmental tests, radon documents, surveys, association records and records for major systems. Sort the documents by topic and date. Keep factual records separate from informal opinions.

Then walk through the home with a resale-first plan. My guide to repairs before selling in DuPage County explains how to prioritize buyer-confidence issues without automatically renovating everything.

If a significant problem is discovered, compare three paths with your broker and attorney: repair it before listing, disclose it and price with the condition in mind, or obtain a specialist's written assessment before deciding. The best choice depends on cost, timing, buyer financing, safety and the reliability of the proposed repair.

Disclosure, inspection and contract review serve different purposes

The seller disclosure communicates the seller's actual knowledge. The buyer's inspection evaluates visible and accessible conditions at a specific time. Attorney review and the purchase contract allocate rights, deadlines and remedies. None of these replaces the others.

For sellers, this means a clean inspection does not retroactively excuse an inaccurate disclosure. For buyers, a disclosure marked 'no' does not guarantee that a condition does not exist. The official form itself warns buyers that the seller's lack of awareness is not a guarantee.

What can happen if a seller knowingly violates the Act?

Under Section 55, a seller who knowingly violates a duty under the Act or knowingly provides false information may be liable for actual damages and court costs, and a court may award reasonable attorney's fees to the prevailing party. If the required report is not provided before conveyance, the statute also gives the prospective buyer a right to terminate.

That is why disclosure is a transaction-management issue, not just another form. Early preparation gives the seller, broker and attorney time to resolve uncertainty before it affects an offer or closing.

A practical pre-listing sequence

Four to six weeks before listing, gather property records and identify unanswered questions. Before photography and launch, decide which repairs need estimates or documentation. Before accepting an offer, make sure the state disclosure, radon documents and any applicable lead-based paint forms have been completed and delivered through the transaction process. From contract to closing, report any new material information immediately.

Also prepare a realistic seller net sheet. Disclosure decisions can affect repair budgets, credits and timing, so review the categories in my 2026 DuPage County home-selling cost guide.

Get your DuPage County sale organized before it goes public

I help homeowners in Elmhurst, Glen Ellyn, Wheaton, Lombard, Naperville and nearby western suburbs prepare the property, organize the marketing timeline and coordinate disclosure questions with the seller's attorney. The goal is a well-documented launch that gives qualified buyers confidence without overspending on unnecessary work.

If you are considering a sale, request a property-specific listing consultation or call or text John Salidas at 630-825-9722.

Primary sources

Illinois General Assembly: Residential Real Property Disclosure Act, 765 ILCS 77

Illinois General Assembly: Illinois Radon Awareness Act, 420 ILCS 46/10

Illinois Emergency Management Agency and Office of Homeland Security: Radon resources for real estate transactions

U.S. Environmental Protection Agency: Real Estate Disclosures about Potential Lead Hazards, updated May 27, 2026

Research was checked October 19, 2026. Laws, forms and transaction facts can change. Confirm current requirements with your Illinois real estate attorney.