Illinois Radon Disclosure Requirements for Home Sellers (2026)

Illinois has specific radon disclosure laws that apply to all residential sellers — FSBO or represented. The Illinois Radon Awareness Act (420 ILCS 46) requires sellers to provide buyers with specific radon information before signing a purchase contract. Here's exactly what's required and how to comply.

What Illinois Law Requires

Under the Illinois Radon Awareness Act, sellers of residential real property must provide buyers with:

• Illinois Emergency Management Agency (IEMA) radon disclosure brochure ("Illinois Radon Facts" or equivalent IEMA-approved disclosure document) — before signing the sales contract
• Written disclosure of any radon test results you have for the property
• Written disclosure of any radon mitigation systems installed in or on the property

If you have had the property tested for radon, you must disclose the test results. If a mitigation system was installed, you must disclose its existence.

What You Are NOT Required to Do

Illinois does NOT require sellers to:

However, disclosing that you've "never tested" when radon risk in your area is well-documented is different from disclosing test results that show elevated radon. If you've tested and results show elevated radon (4 pCi/L or higher), buyers will typically negotiate a mitigation credit or require mitigation as a condition of the contract.

Illinois Radon Risk — Which Areas Are Highest?

The Illinois Emergency Management Agency designates radon potential by county. Illinois has significant radon risk, particularly in northern and central Illinois:

High radon potential zones (Zone 1, average indoor radon >4 pCi/L):

What affects radon levels in a specific home:

If Your Home Has Elevated Radon

If prior testing shows radon at or above 4 pCi/L (EPA action level), you have several options:

If you install a mitigation system, disclose the system's existence, installation date, and most recent test results. Buyers (especially those with VA loans, which require radon testing in certain geographic areas) will want current test documentation.

Radon Disclosure in the Purchase Contract

The standard Illinois Residential Real Property Disclosure Report (required under 765 ILCS 77) includes questions about:

Complete these questions accurately. Misrepresentation on the disclosure form creates post-closing liability.

The IEMA Radon Brochure

The Illinois Emergency Management Agency publishes the required radon disclosure brochure. Download the current version at iema.illinois.gov before signing any purchase contract — you're required to provide this to buyers before contract execution, not at closing.

Radon and VA Loans

VA loans require radon testing in areas designated as Zone 1 (highest risk) by the EPA. Cook County falls in areas where lenders may require radon testing as a condition of VA loan approval. If you expect VA buyers (common in the Chicago metro due to Great Lakes Naval Station in North Chicago and other military connections), budget for radon testing and potentially mitigation if results are elevated.