24 CFR § 882.509 - Overcrowded and under occupied units.

If the PHA determines that a Contract unit is not decent, safe, and sanitary by reason of increase in Family size, or that a Contract unit is larger than appropriate for the size of the Family in occupancy, housing assistance payments with respect to the unit will not be abated; However, the Owner must offer the Family a suitable alternative unit should one be available and the Family will be required to move. If the Owner does not have a suitable available unit, the PHA must assist the Family in locating other standard housing in the locality within the Family's ability to pay and require the Family to move to such a unit as soon as possible. In no case will a Family be forced to move nor will housing assistance payments under the Contract be terminated unless the Family rejects without good reason the offer of a unit which the PHA judges to be acceptable.