A lease application is the point at which a landlord decides between people, and it is therefore the point at which the process matters more than the judgement. The protection against a fair-housing complaint is not good intentions, it is a written standard applied identically and a file that shows it was. This page is how to run that, for a landlord with one unit or twenty.
Write the criteria before you advertise
Income relative to rent, acceptable references, how you treat past evictions or judgements if you consider them at all, and what evidence you require for each. Written before you see any applicants, they are criteria. Written afterwards they are a justification, and everybody including you will know the difference. Keep the written version, because it is what demonstrates the standard existed.
Ask everybody the same questions
The same form, the same follow-ups, the same verification steps. Where you make an exception, record what it was and why. Most fair-housing problems are not a decision made on a prohibited ground; they are two applicants treated differently for reasons nobody wrote down, leaving the difference to be explained by whatever the complainant proposes.
Decide on the criteria, then record the decision
Note which criterion an unsuccessful application failed. That single line is what makes the file coherent later, and it takes a few seconds at the moment you already know the answer. A file of applications with no decisions recorded is worse than no file, because it shows the process existed and cannot show it was followed.
The adverse-action step
If you decline an applicant based in whole or in part on a consumer report, federal law requires you to tell them so, identify the agency that supplied it, and tell them they may dispute it and get a free copy. That step is easy to miss because the decision feels like yours rather than the report's. It is owed whenever the report contributed.
Questions people ask about lease application
Can I refuse an applicant with a low credit score?
You can apply a consistent financial standard. What you cannot do is apply it to some applicants and not others, and if a consumer report informed the decision the adverse-action notice is owed.
Must I give a reason for refusing?
Outside the consumer-report case, generally not, though several jurisdictions now require one. Recording the reason for yourself is worth doing regardless.
How do I handle a co-signer or guarantor?
Apply a written standard to them too, and have them sign their own undertaking rather than adding a name to the tenant's signature block.