The short answer as to whether a landlord must rent to a sex offender is "no." However, nothing in the landlord-tenant arena is ever that simple. Let's unpack this question a bit more, because it is possible for you to get in trouble for not renting to a sex offender.
Landlords have rights
While it's true, as it should be, landlords must treat all applicants fairly and never discriminate based on the seven protected classes -- race, color, national origin, religion, sex, familial status, and disability -- telling landlords who they're required to rent to is crossing a line.
Landlords should -- and do -- have the right to choose their tenants in almost every jurisdiction in the country. There are exceptions, such as Seattle, where a fairly new law called the "first-in-time rule," or the FIT rule, requires landlords to rent to the first qualified applicant. But that law is unique to Seattle. (Seattle landlords: Study this law so you'll know how to comply.)
In almost every other state and jurisdiction, landlords are free to choose their tenants. Best practices call for landlords to make this a business decision, such as determining whether an applicant is in a financial position to make the rent payments based on their credit score, income, and past rental history and not basing this decision on purely personal reasons. But what about an applicant with a history of being a sex offender? How does that come into play?
Be careful with your selection process
Whenever you deny a rental applicant for anything other than business reasons like income and rental history, you run the risk of a lawsuit (whether it's fair and valid or not).
So denying an applicant who otherwise would qualify for your rental only because you find they're on the sex offender registry is not enough of a reason to deny that applicant. In fact, federal law states people on the sex offender registry cannot be denied housing just because they are a registered sex offender.
How to know if an applicant is a sex offender
You can ask whether your applicant is a sex offender on your rental application. Whether the applicant answers "yes" or "no," you can look them up using the National Sex Offender Search on the Department of Justice website. If the applicant lied about being a sex offender, you can deny the application. Lying on a rental application is grounds to deny the application.
If they answered "yes," remember: You cannot deny an applicant just because they are on the registry.
There could be extenuating circumstances, such as if the applicant with a sex offender status poses a current potential danger to nearby residents.
For example, if the sex offender in question has had a recent violation that involved a child, and your property is close to a school or is a multifamily building and children live there, you'd probably have a valid claim this person presents a risk. In fact, if you knowingly rented to a person with that sort of criminal history and they violated a child near your rental, you could be sued by the victim's family. This clearly would be a risk you would not be expected to take.
But if, for example, said sex offender is on the registry for an offense from 10 years ago when they were 18 and had sex with their 17-year-old girlfriend -- and they've had a perfect record ever since -- you might lose a court case if you don't rent to that person just because they are a registered sex offender.
The bottom line
If you're unsure of what to do in a situation where you have a qualified applicant with a sex offender status, you might want to visit your local police department and ask whether it would be safe to put this person in your property.