24 C.F.R. § 8.27

(a) Owners and managers of multifamily housing projects having accessible units shall adopt suitable means to assure that information regarding the availability of accessible units reaches eligible individuals with handicaps, and shall take reasonable nondiscriminatory steps to maximize the utilization of such units by eligible individuals whose disability requires the accessibility features of the particular unit. To this end, when an accessible unit becomes vacant, the owner or manager before offering such units to a non-handicapped applicant shall offer such unit:

(1) First, to a current occupant of another unit of the same project, or comparable projects under common control, having handicaps requiring the accessibility features of the vacant unit and occupying a unit not having such features, or, if no such occupant exists, then

(2) Second, to an eligible qualified applicant on the waiting list having a handicap requiring the accessibility features of the vacant unit.

(b) When offering an accessible unit to an applicant not having handicaps requiring the accessibility features of the unit, the owner or manager may require the applicant to agree (and may incorporate this agreement in the lease) to move to a non-accessible unit when available.