24 C.F.R. § 982.317

(a) A family leasing a unit with assistance under the program may enter into an agreement with an owner to purchase the unit. So long as the family is receiving such rental assistance, all requirements applicable to families otherwise leasing units under the tenant-based program apply. Any homeownership premium (e.g., increment of value attributable to the value of the lease-purchase right or agreement such as an extra monthly payment to accumulate a downpayment or reduce the purchase price) included in the rent to the owner that would result in a higher subsidy amount than would otherwise be paid by the PHA must be absorbed by the family.

(b) In determining whether the rent to owner for a unit subject to a lease-purchase agreement is a reasonable amount in accordance with § 982.503, any homeownership premium paid by the family to the owner must be excluded when the PHA determines rent reasonableness.