Radon Disclosure Laws: What Sellers Are Required to Tell Buyers

Radon disclosure in real estate is not governed by a single federal law. Instead, a patchwork of state statutes, administrative rules, and general real estate disclosure obligations creates a varied landscape in which seller requirements differ dramatically by state. In some states, sellers must proactively disclose any known radon test result above a threshold. In others, radon disclosure falls under the general duty to disclose material defects — and sellers who know about elevated radon and say nothing may face post-closing liability even without a specific radon statute.

No Federal Radon Disclosure Law for Residential Sales

Federal law does not mandate radon disclosure for the sale of private residential property. The Indoor Radon Abatement Act of 1988 directed EPA to develop guidance but created no seller disclosure obligation. The Real Estate Settlement Procedures Act (RESPA) and Truth in Lending Act (TILA) govern financial disclosures in real estate transactions but do not address radon. The only federal radon disclosure requirement applies to HUD-assisted housing, where tenants and buyers must be notified of known radon hazards.

Three Types of State Radon Disclosure Frameworks

Type 1: Specific Radon Disclosure Statute

Some states have enacted radon-specific disclosure statutes that explicitly require sellers to disclose radon-related information. Requirements vary by state but may include:

• Disclosure of any known radon test result (regardless of level)
• Disclosure of any known radon test result at or above the EPA action level
• Disclosure of the presence of a radon mitigation system
• Provision of the EPA “Home Buyer’s and Seller’s Guide to Radon” pamphlet
• Disclosure of whether any test has ever been conducted in the home

States with explicit radon disclosure statutes or regulations include (as of 2026): Florida, Illinois, Maine, Virginia, and others. Statute specifics change — verify current requirements with your state real estate commission or a licensed real estate attorney.

Type 2: General Material Defect Disclosure

Nearly all states require sellers to disclose known material defects in the property — conditions that would affect the property’s value or a buyer’s decision to purchase. In states without a radon-specific disclosure law, elevated radon can still constitute a known material defect that must be disclosed under the general duty.

The key word is “known.” A seller who has never tested does not have a disclosure obligation they are not aware of. A seller who tested five years ago, found 12 pCi/L, and never mitigated or disclosed — that is a different legal situation in most states, regardless of whether a radon-specific law exists. Courts in multiple states have found liability under general misrepresentation or fraud theories when sellers concealed known radon test results even without state radon disclosure statutes.

Type 3: No Specific Requirement (Buyer Beware)

A smaller number of states have neither a specific radon disclosure statute nor a general material defect disclosure requirement robust enough to clearly cover radon. In these states, the buyer’s primary protection is their own due diligence — testing during the inspection contingency period. Buyers in these states should always include a radon contingency in their purchase offer and conduct independent testing.

What Sellers Should Disclose (Best Practice, All States)

Regardless of state-specific requirements, the following disclosure approach protects sellers from post-closing liability and reflects ethical practice:

• Disclose all known radon test results — not just recent ones and not just elevated ones
• Disclose the presence of any radon mitigation system, including the type, installation date, and contractor
• Disclose whether the home has ever been tested and what the results were
• Provide copies of all test reports and post-mitigation testing documentation
• Do not selectively disclose only favorable results while omitting unfavorable historical tests

Sellers who test before listing — and mitigate if needed — have the most straightforward disclosure position: known test results, documented mitigation, confirmed post-mitigation levels. The paper trail protects against post-closing claims.

What Buyers Should Know

• Include a radon contingency in your offer: Specifies the test protocol, the threshold (typically 4.0 pCi/L), and the remedies available to you if the threshold is exceeded
• Conduct independent testing: Do not rely on seller-provided test results as your only verification — even in states where sellers are required to disclose, the seller’s test may be old, improperly conducted, or selectively presented
• Request all historical test results: Ask specifically for all test results ever conducted — not just the most recent one
• Verify any existing mitigation system: Request contractor documentation, post-mitigation test results, and check that the U-tube manometer shows the system is operating

Frequently Asked Questions

Am I required to disclose radon when selling my house?

It depends on your state. States with radon-specific disclosure statutes require disclosure of known results; most other states require disclosure of known material defects that would affect a buyer’s decision — which elevated radon likely qualifies as. Consult a real estate attorney in your state for specific obligations. As a practical matter, failing to disclose known elevated radon exposes sellers to post-closing litigation risk in most jurisdictions even where no specific statute exists.

Do I have to disclose old radon test results?

Yes, if you are aware of them. “Known material defect” disclosure obligations apply to all known information — not just recent or convenient information. A radon test result from 10 years ago showing 15 pCi/L, followed by no mitigation or retesting, is a known condition that almost certainly triggers disclosure obligations under either specific radon statutes or general defect disclosure requirements.

What if the seller did not disclose a known radon problem?

If a seller knew about elevated radon and failed to disclose it in a state with a disclosure obligation (either radon-specific or general material defect), the buyer may have grounds for post-closing claims including fraud, misrepresentation, or breach of contract. Remedies vary by state but may include cost of mitigation, diminution in property value, or in egregious cases, rescission of the transaction. Consult a real estate attorney in your state with the specific facts of the situation.