Cal. Health and Safety Code § 50052.5

(a) For any owner-occupied housing that receives assistance prior to January 1, 1991, and a condition of that assistance is compliance with this section, “affordable housing cost” with respect to lower income households may not exceed 25 percent of gross income. (b) For any owner-occupied housing that receives assistance on or after January 1, 1991, and a condition of that assistance is compliance with this section, “affordable housing cost” may not exceed the following: (1) For extremely low income households the product of 30 percent times 30 percent of the area median income adjusted for family size appropriate for the unit. (2) For very low income households the product of 30 percent times 50 percent of the area median income adjusted for family size appropriate for the unit. (3) For lower income households whose gross incomes exceed the maximum income for very low income households and do not exceed 70 percent of the area median income adjusted for family size, the product of 30 percent times 70 percent of the area median income adjusted for family size appropriate for the unit. In addition, for any lower income household that has a gross income that equals or exceeds 70 percent of the area median income adjusted for family size, it shall be optional for any state or local funding agency to require that affordable housing cost not exceed 30 percent of the gross income of the household. (4) For moderate-income households, affordable housing cost shall not be less than 28 percent of the gross income of the household, nor exceed the product of 35 percent times 110 percent of area median income adjusted for family size appropriate for the unit. In addition, for any moderate-income household that has a gross income that exceeds 110 percent of the area median income adjusted for family size, it shall be optional for any state or local funding agency to require that affordable housing cost not exceed 35 percent of the gross income of the household. (c) The department shall, by regulation, adopt criteria defining, and providing for determination of, gross income, adjustments for family size appropriate to the unit, and housing cost for purposes of determining affordable housing cost under this section. These regulations may provide alternative criteria, where necessary to be consistent with pertinent federal statutes and regulations governing federally assisted housing. The agency may, by regulation, adopt alternative criteria, and pursuant to subdivision (f) of Section 50462, alternative percentages of income may be adopted for agency-assisted housing development. (d) With respect to moderate- and lower income households who are tenants of rental housing developments and members or shareholders of cooperative housing developments, or limited equity cooperatives “affordable housing cost” has the same meaning as affordable rent, as defined in Section 50053. (e) Regulations of the department shall also include a method for determining the maximum construction cost, mortgage loan, or sales price that will make housing available to an income group at affordable housing cost. (f) For purposes of this section, “area median income” shall mean area median income as published by the department pursuant to Section 50093. (g) For purposes of this section, “moderate income household” shall have the same meaning as “persons and families of moderate income” as defined in Section 50093. (h) For purposes of this section, and provided there are no pertinent federal statutes applicable to a project or program, “adjusted for family size appropriate to the unit” shall mean for a household of one person in the case of a studio unit, two persons in the case of a one-bedroom unit, three persons in the case of a two-bedroom unit, four persons in the case of a three-bedroom unit, and five persons in the case of a four-bedroom unit.