A radon test can become part of the inspection discussion after a buyer makes an offer. Reviewing any existing results and considering testing during listing preparation gives the seller more time to address the question.
Testing and the sale process
No. The state rule that governs radon in Indiana is a licensing rule. It says who may test and mitigate, not that a house has to be tested before it is sold.
What drives the test is the buyer, or the buyer's lender, inside the inspection period.
The state licensing rule
The Indiana Department of Health rule is written about the people doing the work. No person or entity may test, analyze, or mitigate for radon in a building unless they are, or have in their employ, an individual certified to perform such services in accordance with the rule. It sets out categories: secondary radon testers, primary radon testers, radon laboratories and radon mitigators.
There is an exemption, and it is the one homeowners ask about. A person testing or mitigating for radon is exempt from the rule if the person is doing it in a building that the person owns and occupies. So a seller can put a kit in his own basement.
The person a buyer sends has to be licensed.
The number everything turns on
The federal action level is the figure that decides what happens next. The EPA says to fix the home if the radon level is 4 picocuries per liter or higher. It also estimates that nearly one out of every 15 homes in the United States has an elevated level, meaning 4 pCi/L or more.
That is the arithmetic behind why this comes up here at all.
What the EPA tells a seller to do
Plainly: test the home before putting it on the market and, if necessary, lower the radon levels. The same guide tells the buyer to know what the indoor level is in any home they consider buying, and to ask the seller for their test results. Two instructions, pointed at the two sides of the same transaction, and the seller's one comes first in time.
Why I raise it before the sign goes up
Because the alternative is meeting it on day eight of an inspection period, with a number in hand, a buyer who is now nervous, and no time to do anything but negotiate. A seller who tested in advance has three ordinary choices and a month to make them. A seller who gets the result inside a contract has one conversation, and it is about money.
A mitigation system is a known quantity. It is a pipe, a fan and a label on it. Installed and documented before a buyer ever asks, it reads as maintenance. Installed under a contract deadline after a bad reading, the same system reads as a problem that was found.
Nothing about the house changed between those two sentences.
Where the home has never been tested, discuss testing before listing, including for a finished basement used as a bedroom. A result can then be reviewed with the appropriate professional before the inspection timetable is part of a contract.
What a reading means for anyone's health, which mitigation method fits a particular foundation, and what has to be disclosed in your sale are not mine. The first belongs to a physician and to the state health department, the second to a licensed mitigator, the third to your attorney.
The notes on what a home inspection covers, the Indiana seller disclosure form and what gets done before the photographer comes cover the rest of the pre listing work, and the sellers page sets out how a listing is prepared.
Sources: Indiana Department of Health, Final Rule, LSA Document #21-23, adding 410 IAC 5.1-1-22 through 410 IAC 5.1-1-26 on radon testers, radon laboratories and radon mitigators; and United States Environmental Protection Agency, Buying a New Home: How to Protect Your Family From Radon, EPA 402/K-24/001, March 2024. Read at source, October 7, 2026.
This note is general. It is not health, legal or environmental advice, and it is not a statement of what any particular sale requires.