The Radon Rule Carmel Sellers Keep Getting Wrong

A seller called us this spring convinced that Indiana had just passed a law requiring every home sale to include a radon test. She had read it on an inspection company's website, complete with a specific effective date in the summer of 2026. She wanted to know if she needed to get ahead of it before listing her Carmel home.

She didn't need to get ahead of anything. That law doesn't exist. Lawmakers tried to pass something close to it twice in two years, and both times the bill never even got a hearing.

That gap between what people think the rule is and what the rule actually is matters more in Carmel than almost anywhere else in the state, and not for the reason most sellers assume.

What Almost Became Law This Year

The bill in question was Senate Bill 61, authored by Senator Greg Taylor and referred to the Senate Judiciary Committee. It would have required a seller's agent to hand buyers a written radon warning statement from the Indiana Department of Health, disclose any known radon test results or mitigation history in writing, and give buyers a state-published guide on radon testing before a purchase agreement could be signed.

The Hoosier Environmental Council tracked the bill closely and put it plainly in its own legislative summary: an identical version had already died without a hearing in the 2025 session, and SB 61 met the same fate in 2026. The full Indiana General Assembly session adjourned Sine Die on February 27, 2026, and the bill's status never moved past "referred to committee." On the state's own bill tracker, it's marked inactive.

So the version of the law that some marketing copy describes as already in effect simply isn't. What sellers are left with is the older, lighter standard that's been on the books for years.

What Indiana Law Actually Requires Today

Every seller of a one to four unit residential property in Indiana still has to complete the Seller's Residential Real Estate Sales Disclosure, State Form 46234, and get it to the buyer before an offer is accepted. Radon is one of the items on that form, alongside things like foundation condition, water intrusion, and known hazardous materials.

The standard is your current actual knowledge as of the day you sign, not the results of an inspection you're required to commission. If you've never tested, you're not lying by marking the radon section unknown. If you have tested and know the number, you have to say so.

Two details trip sellers up more than any others:

• Selling "as-is" does not remove the disclosure obligation. An as-is clause changes whether a buyer can ask you to make repairs after an inspection. It has nothing to do with your legal duty to say what you know before they ever make an offer.
• If something changes between when you deliver the disclosure and when you close, Indiana law requires you to update it. You're certifying at settlement that the property's condition is substantially the same as when you first disclosed.

None of this requires a radon test. It never has. What it requires is honesty about what you already know.

Why the Statehouse Debate Undersells the Carmel Reality

Here's where the picture gets more interesting than a simple pass or fail vote in the Statehouse.

Indiana's own Department of Health has estimated for years that nearly one in three homes in the state test above the EPA's action level of 4.0 picocuries per liter, the threshold at which the agency recommends fixing the problem. Hamilton County is widely identified by local radon professionals as sitting in the EPA's highest risk tier, Zone 1, which the agency defines as counties with a predicted average indoor screening level above that same 4.0 pCi/L mark.

Radon's most common entry points are foundation cracks, sump pits, and the joints where a basement floor meets its walls. That's not a coincidence in a market like Carmel. Basements aren't a minor feature here, they're a meaningful chunk of a home's value. Data on Carmel's single-family market in the first quarter of 2026 shows homes with a basement averaging $731,000, compared to $456,450 for homes without one. That's not a rounding difference. It's the single largest structural variable in what a Carmel house is worth.

Put those two facts together and the shape of the problem becomes clear. The feature that adds the most value to a Carmel listing is the same feature that gives radon its easiest way into the house. A seller who skips testing because the law doesn't require it isn't avoiding a legal risk, they're walking into a negotiation with buyers who almost certainly will test anyway, and doing it with less information than the person sitting across the table.

What a Realistic Timeline Looks Like

Buyers in this market routinely request radon testing as part of their inspection contingency even though nothing in Indiana law forces them to. Most agents who work Hamilton County regularly see it as a near-default step, not an exception.

If you're preparing to list a Carmel home with a basement, here's what the process typically looks like from a seller's side:

1. Order a test before you list, not after an offer comes in. A short-term test as part of a pre-listing inspection typically runs $150 to $250.
2. If the result comes back at or above 4.0 pCi/L, you have real information to put on your disclosure form rather than a guess.
3. If mitigation is warranted, a standard sub-slab depressurization system for a typical Carmel basement generally falls in the $1,000 to $1,500 range, with the broader range for more complex foundations or crawl spaces running $800 to $2,000.
4. After installation, a follow-up test confirms the system brought levels down, giving you a documented result to hand a buyer instead of an open question.

None of this is required by statute. All of it changes how a negotiation goes.

The Traps That Actually Cost Sellers

The legal risk in Indiana isn't a missed testing requirement, it's what happens after a seller either guesses wrong or leaves something out on purpose. Indiana courts have held that a seller isn't liable for a mistake they made in good faith without actual knowledge, but a seller who knowingly hides a known problem on the disclosure form opens themselves up to a fraud claim, not just a failed sale.

A few patterns show up more than others:

• Marking "unknown" on the radon question when you've actually had a system installed or a test run in the past. That's not protection, it's the kind of omission that looks intentional if it surfaces later.
• Assuming an as-is sale means you can skip the form altogether. It doesn't.
• Treating a prior mitigation system as ancient history rather than something worth disclosing along with when it was installed and whether it's still functioning.

The safest version of all of this is also the simplest. Test early, keep the paperwork, and answer the form based on what you actually know rather than what you'd prefer a buyer not ask about.

A Few Straight Answers

Do I have to test my Carmel home for radon before selling? No. Indiana law doesn't require a test. It requires you to disclose whatever you already know. Most buyers in this market will request their own test regardless, so going in with your own results tends to work in your favor.

Does listing "as-is" get me out of the radon disclosure requirement? No. An as-is clause limits what repairs a buyer can demand after inspection. It does not change your obligation to disclose known conditions on Form 46234 before they make an offer.

What if my test comes back high right before closing? You're required to update your disclosure if the property's condition changes materially before settlement. A late high reading doesn't disappear because you already handed over the original form. It becomes a new conversation, and usually a negotiation over who handles mitigation before the deal closes.

This kind of thing, the difference between what a headline implies and what the actual statute says, is exactly where a good agent earns their fee. If you're weighing when to list a Carmel home with a basement, or you just want a straight read on what your specific disclosure form should say, Morton Homes Realty is happy to walk through it with you before you're staring at a buyer's inspection report and wondering what you're required to say.