In most cases, the person who owns the home when the radon system goes in pays for it. Homeowners insurance does not cover it. No federal law makes a seller fix it. In a home sale, the cost goes to whoever negotiates it into the contract: the seller pays, the buyer gets a credit, the two split it, or the buyer takes it on after closing. This guide explains each scenario and the paperwork that decides it. It also covers one financing route many buyers never hear about.
TL;DR
- Radon mitigation is a private expense. The property owner pays, and standard homeowners insurance treats it as maintenance, not a covered loss.
- In a sale, there is no federal rule on who pays. The purchase contract decides, so a radon testing contingency is the buyer's main protection.
- If a buyer does not negotiate it in writing, the buyer is generally responsible for the cost after closing.
- A HUD 203(k) loan can roll mitigation into a mortgage when the total improvements meet the program's minimum.
- Whoever pays, insist on post-installation verification testing. It is the only proof the system worked.
Table of Contents
- The default answer: the property owner
- Does homeowners insurance pay for radon mitigation?
- Buying or selling: the contract decides
- Why sellers often choose to fix it first
- Buyers: three ways to handle a failed test
- What mitigation costs, and what changes the price
- Can you finance it? The HUD 203(k) route
- Rental, multifamily and commercial properties
- Our perspective: pay once, verify, document
- Get a quote you can bring to the negotiating table
- FAQ
- Sources
The default answer: the property owner
Radon is a naturally occurring gas that seeps up from soil and rock and into a building. When a test shows it above the EPA action level of 4 pCi/L, fixing it is the owner's job, like a failing furnace or a leaking roof. According to the CDC, radon is the second leading cause of lung cancer in the US, and no level is known to be completely safe. That is why the goal is the lowest level you can reasonably reach, not just a number under 4.
For a homeowner who is not selling, the picture is simple. You test, you hire a qualified contractor, you pay, and you verify the result. There is no landlord to bill, no builder warranty to invoke on an older house, and no public program that sends a crew to your door.
The question gets more interesting in three situations: when you have insurance, when you are buying or selling, and when the upfront cost is a stretch.
Does homeowners insurance pay for radon mitigation?
Generally, no. A standard homeowners policy covers named perils such as fire, smoke and theft. Radon accumulating in a house is a long-term condition, and insurers classify the testing and the system as property maintenance. EPA guidance for home buyers and sellers is the source we rely on for how radon is treated in the purchase process.
Two practical notes:
- Read your own policy. Wording varies, and your agent can tell you in one phone call whether anything in your policy touches radon. Do not assume coverage because you pay for a broad plan.
- Do not confuse radon with other coverage. Some policies include ordinance or law coverage, which pays extra to rebuild to updated building codes, as the NAIC homeowners insurance glossary describes. That applies after a covered loss. It is not a way to bill an insurer for a radon fan.
If you are shopping for a policy, ask the agent directly how radon is handled. A clear answer now beats a surprise later.
Buying or selling: the contract decides
This is where most of the confusion lives, and where the most money moves. There is no federal law requiring a seller to mitigate radon. According to HUD's guidance for buyers, responsibility is settled by what the purchase agreement says. EPA advises that the contract should spell out who will test, what type of test is used, and who pays for mitigation if it is needed.
Some states and local rules add disclosure duties, and forms differ by region and by agent. Your agent or real estate attorney should confirm what applies to your transaction. But disclosure is not the same as payment. A seller who discloses a high reading still does not have to fix it unless the contract says so.
The four common outcomes
| Outcome | How it works | Who ends up paying |
|---|---|---|
| Seller mitigates before closing | The seller hires a contractor, completes verification testing, and hands over documentation | Seller |
| Credit or price reduction | The buyer takes the house as is and receives money off the price or at closing | Seller, indirectly |
| Split | Both sides agree to share the cost, often up to a cap | Both |
| Nothing negotiated | The buyer closes without a radon term | Buyer, after closing |
The last row is the trap. When nothing is negotiated, the buyer is generally responsible for the cost once the keys change hands. A contingency is cheap insurance against that.
What a good radon contingency includes
EPA's Home Buyer's and Seller's Guide to Radon suggests contract provisions on who conducts the test, what type of test to use, when to do it, and how the parties will handle the results. In practice, build your clause around these points:
- Who tests. A qualified, independent professional, with the test placed under proper conditions.
- The trigger. Most contracts use the 4 pCi/L action level. We cover how that line plays out in a negotiation in our post on radon contingency clauses for buyers and sellers.
- The remedy. Seller mitigates, seller credits, price reduction, or the buyer may walk away.
- The standard of work. The system should be designed for the foundation, installed to a recognized standard, and followed by a verification test.
- The paperwork. Results and installation records handed over at closing, so the next sale is not a problem.
Timing matters
Test early. EPA advises getting the radon test done as soon as possible in the transaction, because a late surprise squeezes everyone. A short inspection window leaves little room to get quotes, and a closing date can slip while people argue over a fix.
Why sellers often choose to fix it first
EPA guidance treats the period before listing as the best time to deal with radon. A seller who mitigates ahead of time removes the risk of a high result landing in the middle of a closing, which can trigger delays or a renegotiation at the worst moment. It also lets the seller hand a buyer a clean verification report instead of a debate.
That is a business decision as much as a safety one. A mitigation system is a modest, concrete project compared with a remodel. If you are weighing which pre-listing projects are worth the money, one agent's take on why sellers can skip big remodels before listing is a useful companion read, though it is written for a different market. Radon testing and a documented fix are the kind of low-drama item buyers and their agents tend to appreciate.
If you are listing a home, we handle radon testing and mitigation during a home sale, including documentation suited to real estate transactions.
Buyers: three ways to handle a failed test
Say you are under contract and the test comes back above 4 pCi/L. You have options, and you do not have to panic.
- Ask the seller to mitigate. Make sure the work will be done by a qualified contractor with a design that fits the foundation, and that verification testing is in scope. Ask for the report.
- Ask for a credit or price reduction. This puts you in control of the contractor choice. Get a written quote before you set the number, so the credit matches real costs.
- Walk away, if your contingency allows. Only possible if you wrote that right into the contract.
Before accepting a seller's own contractor, ask what the scope includes. EPA's Consumer's Guide to Radon Reduction advises choosing a state certified or qualified mitigation contractor, and starting with your state radon office, since many states require radon professionals to be licensed or certified.
One more caution: do not lean on a neighbor's number. EPA warns against using test results from other homes to estimate yours, because even next-door houses can differ widely.
What mitigation costs, and what changes the price
EPA's Citizen's Guide to Radon says the cost depends on how the home was built and describes an average house at roughly $1,200, a figure from a much older edition that today's prices usually exceed. Treat it as a floor on scale, not a quote. We do not publish a price list, because the work is designed for each house. What we do offer is a fixed written quote after we measure the site, with no added costs after quoting. Our Cincinnati radon mitigation cost guide explains the factors in detail.
The main drivers:
- Foundation type. A slab, a basement, a crawl space and a fieldstone foundation each need a different approach. See our posts on crawl space radon and radon in old homes.
- What is under the house. Soil and rock affect how easily gas moves and how many suction points are needed.
- Layout and routing. Where the pipe runs and where the fan sits change labor and materials.
- Verification. Reputable work ends with a second test. A low-ball quote that skips it is not actually cheaper.
Can you finance it? The HUD 203(k) route
If the upfront cost is the obstacle, there is a lesser-known option. EPA's radon and real estate resources page explains that radon reduction is an improvement that can be financed through a HUD Section 203(k) mortgage, which is a program for rehabilitating and improving single-family homes. The financing rolls the work into one mortgage.
There are conditions. The total improvements generally have to meet a minimum threshold, typically $5,000, so radon alone may not qualify, but it can be part of a larger repair list. Rules, caps and lender participation change, so ask a 203(k)-experienced lender before you build a plan around it.
HUD also has its own radon expectations for projects it funds. Its environmental review notice calls for mitigation when testing finds levels at or above 4 pCi/L. If a lender is involved, ask early whether it has radon conditions. Lender requirements can make the buyer pay for the test and treat mitigation as a loan condition.
Rental, multifamily and commercial properties
Our audience is owners, not renters, and the rule holds: the property owner is the one who answers for the building. If you own a multifamily or commercial property, radon can show up in underwriting and sale diligence. We cover how to get ahead of that in our posts on radon in apartments for multifamily owners and commercial radon mitigation. For new construction, a rough-in during the build is far easier than retrofitting later, and the builder or owner who orders it pays for it.
Our perspective: pay once, verify, document
We focus on radon mitigation and nothing else, and the same pattern comes up in every cost conversation. People ask who pays, but the better question is what they are paying for. A system is only worth its price if it is designed for the specific foundation, installed to ANSI/AARST standards, and proven with a post-installation test.
Here is how that shapes what we do:
- Site-specific design. We measure and design around the house in front of us, not a template.
- Fixed written quotes. The number you sign is the number you pay.
- Verification in every job. Every mitigation includes a post-installation test, so there is a result on paper.
- Documentation for the deal. Buyers, sellers and agents get records suited to a real estate transaction.
The cheapest quote is rarely the lowest cost. A system that does not bring levels down means paying twice. And because winter closes houses up and tends to push readings higher, an October to February test often shows the real picture. A 13-year study published by the CDC found peak concentrations in January and the lowest in July.
— Yoshua
Get a quote you can bring to the negotiating table
Whether you are a seller who wants a clean report, a buyer who needs real numbers for a credit request, or an owner who just tested high, start with a radon test. If the result calls for action, our radon mitigation systems are designed per foundation and come with a fixed written quote and verification testing. Already have a system that seems off? See our page on radon system repair and fan replacement, or read our checklist for a mitigation system that is not working.
FAQ
Does the seller have to pay for radon mitigation?
Not by federal law. There is no federal requirement for a seller to fix radon, so the purchase contract sets the rule. Buyers who want the seller to pay should include a radon contingency that names the test, the action level and the remedy.
Will home insurance cover radon mitigation?
Usually not. Standard homeowners policies cover specific perils, and radon testing and mitigation are treated as maintenance. Check your own policy wording with your agent to be sure.
Should I buy a house that already has a radon mitigation system?
Often that is a good sign, because someone has already addressed the problem. Ask for the installation records and the post-installation test result, and have the home tested again during your inspection period. If the system is old or the fan is not running, repair or fan replacement may be needed.
What houses are most at risk for radon?
Age and sturdiness are not the deciding factors. According to the CDC, geology and foundation design drive risk. Any home can have elevated levels, so testing is the only way to know.
Sources
- CDC: Reduce radon in your home
- EPA: Home Buyer's and Seller's Guide to Radon (2024)
- EPA: Home Buyer's and Seller's Guide to Radon (NEPIS)
- HUD: For Your Protection
- EPA: Radon and Real Estate Resources
- HUD: CPD Notice on Addressing Radon in the Environmental Review Process
- EPA: Consumer's Guide to Radon Reduction
- EPA: A Citizen's Guide to Radon
- NAIC: Homeowners Insurance
- CDC: 13-year radon seasonality study