Dealing with radon when selling your home can be unexpected, but it's a hurdle many face. The cost to mitigate radon varies, typically ranging from $800 to $2,500, depending on your home's foundation and system complexity. While the seller usually covers this, it can become a point of negotiation. Some buyers may also request retesting after mitigation, adding a few hundred dollars. Planning for this potential expense keeps the sale process smoother. radon cost home sale 9