25 CFR § 700.53 - Dwelling, replacement.
The term replacement dwelling means a dwelling selected by the head of a household as a replacement dwelling that meets the criteria of this section. A replacement dwelling is a dwelling that:
(a) Is decent, safe, and sanitary as described in § 700.55.
(b) May include existing dwellings for resale, new construction, modular homes, mobile homes, mutual self-help housing or other federally assisted housing programs.
(c) Is in an area not subjected to unreasonable adverse environmental conditions from either natural or man-made sources and in an area not generally less desirable than that of the acquired dwelling with respect to public utilities, public and commercial facilities, and schools.
(d) Is available at a purchase price within the ability-to-pay of the displaced person. A replacement dwelling shall be considered within the ability-to-pay of the displaced person if, after he receives a replacement housing payment and any available housing assistance payments, his new monthly housing cost (defined at § 700.81) for the replacement dwelling does not exceed twenty-five percent (25%) of the monthly gross income of all adult members of the household, including supplemental income payments received from public agencies. If the person's monthly income pattern is irregular, the Commission shall base its determination of average gross monthly income on the period of time, actual and/or projected, that most fairly and equitable represents the person's ability-to-pay.
(e) Is actually available to the displaced person on the private market, other federally sponsored housing projects, tribal-sponsored housing projects and/or Commission-sponsored housing projects.