The rules, as published

Disclosure is required by statute. South Dakota Codified Laws §§ 43-4-37 through 43-4-44 require sellers of residential property to complete a disclosure statement covering known hazardous conditions (radon is named, alongside mold, lead paint, and asbestos) and any known testing for them. In plain terms: if the sellers know a radon number for the house, or know a system is installed, it belongs on the form. What the statute does not require is testing. A seller who has never tested has nothing to disclose, which is why so many South Dakota homes get their first-ever radon test during a buyer’s inspection.

Testing in transactions runs on protocol, not regulation. South Dakota has no statutory licensing of radon testers or mitigators. The state radon program provides education and data rather than a contractor registry. So transaction testing leans on national practice: a continuous monitor logging hourly readings over roughly 48 hours, under closed-house conditions, producing a tamper-resistant written report both sides can rely on.

Who pays is a negotiation, not a rule. No South Dakota statute assigns mitigation costs. In practice it resolves like any other inspection item: the buyer requests it, the seller fixes it or credits it, or the parties split the difference. Local custom leans toward the seller handling a confirmed high result, but nothing obligates that outcome.

One plain caveat: this page is researched background, not legal advice. Statutes get amended and contracts vary. For your deal, the people to ask are your agent and, where it matters, a South Dakota real-estate attorney.

Resolving a finding before closing

When a transaction test comes back high, the sequence that follows is compact.

Confirmation testing mostly gets skipped, and that’s reasonable. Guidance suggests confirming borderline results, but a monitored 48-hour test is already the trustworthy version, and contingency windows rarely leave room for a second one. Agents typically treat the monitor’s number as the number.

Then the negotiation, which usually settles within days: seller fixes it before closing, or buyer takes a credit and schedules the work after keys change hands. Both paths work. The seller-fixes path suits deals with time; the credit path suits compressed closings and buyers who want to pick their own installer.

Mitigation itself fits inside most closing timelines. A typical residential install is short work once scheduled, and the system needs to run only briefly before the verification retest can start. The full sequence of install, run, and retest routinely completes inside a normal escrow period when it starts promptly. The enemy is the week nobody acts.

Last comes the paperwork, which is the point of the whole exercise: a written post-installation result below the action level, filed with the transaction documents. That sheet answers the buyer’s lender, the buyer’s future disclosure form, and the buyer’s 2 a.m. doubts, all at once. Coordinating the whole radon piece around a closing is its own small craft, and it goes smoothest when it starts the day the result lands.