There is no federal law covering radon disclosure requirements for home sales, but roughly 37 states and the District of Columbia impose their own rules, and in nearly all of them the obligation is the same: if you have radon test results or a mitigation system in the home, you have to share that information with the buyer in writing before the contract is signed. You generally are not required to test a home that has never been tested. What you cannot do is sit on knowledge of an elevated reading and stay quiet about it.
No Federal Radon Disclosure Rule
Radon is often confused with lead-based paint, which does carry a federal disclosure mandate. The Residential Lead-Based Paint Hazard Reduction Act requires sellers of most pre-1978 homes to provide a warning statement, hand over any known inspection results, and give the buyer a 10-day testing window before a contract becomes binding. Radon has no equivalent federal statute.
The Indoor Radon Abatement Act of 1988 set a national goal for indoor air quality and authorized the EPA to publish educational materials and fund state radon programs, but it created no testing or disclosure duty for private home sales. The EPA’s role is advisory. Its guidance sets an action level of 4.0 picocuries per liter (pCi/L), the threshold at which it recommends installing a mitigation system, and that number is the one state laws and real estate contracts have organized themselves around.
What Most State Disclosure Laws Require
About 37 states and D.C. require some form of radon disclosure in a residential sale. The specifics vary, but the dominant model is narrow and practical. If you have previously tested the home for radon, you must give the buyer the test results. If you have installed a mitigation system, you must provide documentation of that work. You fill out a disclosure form stating whether you know of elevated concentrations and whether you have handed over all available records.
Under this model, you are not forced to test. The duty is to disclose what you know, not to go find out. A seller who has never tested, has no mitigation system, and has no reason to suspect a problem generally satisfies the law by saying so on the form.
A smaller group of states layers more on top. These states may require the seller to deliver a state-approved pamphlet on radon health risks along with the disclosure, use a standardized form issued by a state agency, or note the property’s placement on the EPA’s radon zone map. Zone 1 counties have the highest predicted average indoor levels, and some disclosures reference that classification directly.
States without a radon-specific statute are not a loophole. They still require sellers to disclose known material defects under general real estate disclosure law. A seller in one of those states who knows levels are high and says nothing can still be sued under fraud or misrepresentation theories.
When Disclosure Rules Don’t Apply
Most state laws exempt certain transfers from the standard disclosure process. The usual carve-outs track the exemptions in the federal lead-paint rule and apply to transactions where the seller has no meaningful knowledge of the property or where there is no arm’s-length buyer at all.
- Court-ordered transfers through probate, bankruptcy, or similar proceedings.
- Foreclosure sales where a lender resells after default.
- Transfers between family members or co-owners, including divorce settlements and gifts to relatives.
- Transfers into a trust or distributions to heirs from an estate.
- New construction in some jurisdictions, since no prior testing data exists.
Confirm the exemption applies to your specific transaction before leaving radon paperwork out of the closing package. Getting this wrong can unwind the sale or create liability on its own.
When and How to Deliver the Disclosure
Timing drives most disclosure disputes. In states that require radon disclosure, you must deliver the completed form and any required educational materials before the purchase contract becomes binding. If the buyer sends an offer before you have provided the disclosures, give them next and allow a reasonable window for review before the contract is finalized.
The buyer signs the form to acknowledge receipt. That signature is your proof that you met the obligation. The signed disclosure then gets attached to the purchase agreement as an addendum. Both sides should keep copies for several years after closing, because property-condition disputes can surface long after the deal closes.
Failing to deliver the required disclosures on time can give the buyer the right to cancel without penalty, depending on state law. A seller who tested, found low levels, and simply forgot to pass along the paperwork can land in the same procedural trouble as one who hid a bad result. Treat the delivery step as seriously as the content.
If the Buyer Tests and Finds Elevated Radon
Even where sellers are not required to test, buyers frequently arrange their own testing during the inspection period. Short-term tests measure radon over 2 to 90 days and are the common choice in real estate deals because the deal timeline rarely accommodates a longer-term test. Professional testing typically runs between $150 and $700.
If the result comes back at or above 4.0 pCi/L, the buyer’s options depend on the contract. Many purchase agreements include a radon contingency allowing the buyer to request mitigation, negotiate a price reduction, or walk away. The two common resolutions are the seller installing a mitigation system before closing and providing a post-installation test below 4.0 pCi/L, or the seller giving a closing credit so the buyer can handle mitigation afterward. Professional installation of a mitigation system generally costs between $800 and $3,000, depending on foundation type, home size, and local labor rates.
Once a mitigation system is installed and documented, it becomes part of what you disclose on the next sale. Keep the installation paperwork and any follow-up test results with your closing file.
A Note on New Construction
If you are selling a home that has never been occupied, the standard radon disclosure framework often does not apply because there is no prior test data to share. That does not mean radon is irrelevant. The EPA recommends that builders include five basic radon-resistant features in new construction: a gas-permeable gravel layer under the slab, plastic sheeting over the gravel, a vertical vent pipe running from the gravel through the roof, caulking at foundation openings, and an attic junction box so a vent fan can be added later if needed. Buyers often ask whether these were installed, and a builder-seller who can answer with documentation is in a stronger position than one who cannot.
What Happens If You Don’t Disclose
A seller who knowingly conceals elevated radon can face meaningful liability. In states with radon-specific disclosure statutes, buyers can typically recover actual damages, including mitigation costs, and some states allow a court to cancel the purchase agreement outright. Sellers may also owe the buyer’s legal fees.
In states without a radon-specific rule, concealment of a known environmental hazard still falls under general fraud and misrepresentation doctrine. A buyer who can prove you knew about elevated radon and said nothing can seek remediation costs, diminished property value, and in serious cases punitive damages. Courts focus on actual knowledge. A seller who never tested and genuinely did not know is in a very different position from one who received a reading of 8.0 pCi/L and filed it away.
The practical rule is simple. If you have test results, disclose them. If you installed a mitigation system, document it and give the records to the buyer. Completing the paperwork costs nothing. Defending a fraud claim after closing is a different kind of bill entirely.