Guide
Is Radon Testing Required to Sell a Home in Illinois?
Updated
No. Illinois does not legally require a radon test before selling a home. What state law does require, under the Illinois Radon Awareness Act (420 ILCS 46/) and the Residential Real Property Disclosure Act, is that a seller disclose a radon test result they already know about. Many buyers, lenders, and agents request testing anyway, which is why it's common even though it isn't mandatory.
What the Radon Awareness Act actually says
The Illinois Radon Awareness Act (420 ILCS 46/) defines radon terms for real estate purposes (what counts as a "radon hazard," what a "radon test" means under state rules) and requires sellers to provide an IEMA-approved disclosure pamphlet summarizing radon testing protocols to buyers. It does not create a legal requirement that a test be performed before a sale.
What a seller has to disclose
Under the Residential Real Property Disclosure Act, a seller who already has a known radon test result generally has to disclose it as part of the standard property disclosure process, the same way other known material defects get disclosed. A seller who has never tested has nothing on record to disclose, which is part of why testing ahead of listing is common practice: it puts the seller in control of a result instead of a buyer's inspector surprising them with one.
Why it's common anyway
Lenders, buyers, and real estate agents frequently request a radon test as a condition of the deal even though state law doesn't mandate one, similar to how a home inspection isn't legally required either but is standard practice. A buyer or their agent can request their own independent test even if the seller already has a result.
Quick answers
FAQ
Can a buyer require radon testing as part of an offer?
Yes. It's a negotiated contingency like any other inspection item, not a state mandate, but it's common enough that most Illinois purchase contracts have a standard radon clause available.
What if the seller already tested and the result was high?
Under the disclosure rules, a known result generally has to be disclosed. Buyers and sellers then typically negotiate a credit, repair, or mitigation arrangement similar to other inspection findings.
Does new construction have different rules?
New construction has its own separate requirement under the Radon Resistant Construction Act, covered in a dedicated guide, but the sale-disclosure rules above apply the same way to a new home resale.
Keep reading
Related guides
Does Illinois Require Radon-Resistant New Construction?
Illinois's 2013 Radon Resistant Construction Act and what it actually requires of new homes, plus why a passive system still needs to be tested.
How to Verify a Radon Tester's Illinois License
Illinois requires an IEMA license to measure or mitigate radon. How the license works and the free public lookup to check one before you book.
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