The decision is the riskiest moment in the whole leasing process, and the denial is riskier than the approval. Most landlords owe a notice at this point that they have never heard of.
Decide against the criteria, not the person
By the time you are deciding, your written criteria should already exist. Lay each applicant against them in the same order and record the result. If you find yourself building a case for or against someone rather than reading a checklist, stop, because that is the moment consistency slips.
Process applications in the order they arrive and tell applicants that is what you do. First qualified applicant gets the offer. It is the simplest defensible rule available, and it removes almost all of the discretion where bias lives.
Making the offer
Approve in writing and be specific: the address and unit, the rent, the deposit, the term and start date, who is on the lease, and a deadline to accept. Say plainly that the offer is contingent on signing the lease and paying the deposit by that deadline.
Do not stop screening the moment someone says yes on the phone. Keep the other qualified applicants warm until the lease is signed and the deposit has cleared, because verbal acceptances fall through regularly.
The denial, and the notice you owe
This is the part that catches people. If you used a screening report and anything in it contributed to the outcome, the Fair Credit Reporting Act requires an adverse action notice. Adverse action is broader than a flat denial: it includes approving with a higher deposit, requiring a co-signer, or offering worse terms than you advertised.
The notice has to include the name, address, and phone number of the screening company, a statement that the company made no decision and cannot explain why you decided as you did, notice of the applicant's right to a free copy of the report within 60 days, and notice of the right to dispute anything inaccurate. If a credit score was a factor, include the score and the key factors affecting it.
Send it even when it feels unnecessary. It costs you one letter, it is legally required, and failing to send one is a straightforward violation with statutory damages attached.
What to say, and what never to write down
Keep the reason factual and tied to your published criteria. "Income was below our stated three times rent requirement" is fine. So is "we approved an earlier qualified applicant."
Never reference a protected characteristic, and be alert to the phrasings that do so accidentally. Comments about children being noisy, whether a neighbourhood would suit someone, an applicant's accent or where they are from, a service animal treated as a pet, or an assumption about how a family will use the space are all fair housing exposure. Say less rather than more, and say the same thing to everyone.
Keep the file
Keep every application, your written criteria, the reports you pulled, the adverse action notices you sent, and a short note of the outcome for each applicant. Most guidance suggests holding these for at least two to three years, and longer where state law says so.
A fair housing complaint can arrive long after you have forgotten the applicant. The file is what turns "I treated everyone the same" from an assertion into evidence. If you would rather the notices be generated and the file assembled for you, that is part of what screening handles.