The Fair Housing Act is the federal law that bars discrimination in renting, selling, or financing housing based on seven protected classes: race, color, religion, sex, national origin, disability, and familial status. It applies to nearly every landlord, including a single-family owner who advertises a vacancy or uses a real estate agent, and it covers how you market a unit, how you screen applicants, the terms you offer, and how you treat tenants during the lease.
In practice
Say you list a two-bedroom unit and get four applications in a week. One comes from a family with two young children. If you set a written policy of two occupants per bedroom, that family of four fits a two-bedroom unit and rejecting them on headcount would run straight into the familial status protection. Now compare applicants on the same neutral standard: income at or above three times the $1,500 rent (so $4,500 monthly), credit pulled the same way for everyone, and the same two prior landlord references requested from each. Applicant A clears at $5,200 income, applicant B at $3,900. You can decline B on the income line because you applied the identical 3x test to all four. You cannot decline B because the household includes children. The test is whether a written, uniform standard explains every yes and every no.
Why it matters to a small landlord
The exposure here is not theoretical. A single complaint can pull you into a federal or state agency investigation, and damages are not capped the way a deposit dispute is. The protection is the boring part: write down your criteria before you advertise, apply them to every applicant in the same order, and keep the notes. That same discipline is what a clean tenant screening process is built on, and it overlaps with how you document tenant interactions once someone is in the unit. A disability request is its own category: you generally must grant a reasonable accommodation unless it imposes an undue burden, and you cannot charge the tenant a fee for it.
State and local law usually stacks more protected classes on top of the federal seven, commonly source of income (which can reach a housing choice voucher), age, marital status, or sexual orientation, so the federal list is the floor and never the ceiling. Read your state and city statutes alongside the federal rule, hold every applicant to the same screening bar, and treat a reasonable accommodation as a request you document and answer, not one you negotiate away.
This is general background, not legal advice. Fair housing rules vary by state and city, and the safest move before you advertise or decline an applicant is to read your local statute or ask a local attorney.