(1) Not less than 20 percent of the total number of units in a multifamily rental housing development financed, or for which financing has been extended or committed, pursuant to this chapter shall be for occupancy on a priority basis by lower income households. If a multifamily rental housing development is located within a targeted area, as described by Section 143(j) of Title 26 of the United States Code, not less than 15 percent of the total number of units financed, or for which financing has been extended or committed pursuant to this chapter, shall be for occupancy on a priority basis by lower income households. Not less than one-half of the units required for occupancy on a priority basis by lower income households shall be for occupancy on a priority basis for very low income households. However, with approval of the board, the agency may waive the priority requirements for very low income households in designated geographic areas of the state upon a determination that the housing needs of a substantial number of lower income households will not otherwise be met. The rental payments on the units required for occupancy by very low income households paid by the persons occupying the units (excluding any supplemental rental assistance from the state, the federal government, or any other public agency to those persons or on behalf of those units) shall not exceed 30 percent of 50 percent of area median income. If the sponsor elects to establish a base rent for all or part of the units for lower income households and very low income households, the base rents shall be adjusted for household size. In adjusting rents for household size, the agency shall either assume that one person will occupy a studio unit, two persons will occupy a one-bedroom unit, three persons will occupy a two-bedroom unit, four persons will occupy a three-bedroom unit, and five persons will occupy a four-bedroom unit, or commencing September 1, 2016, utilize occupancy assumptions that it determines to be appropriate and commercially reasonable for financing extended pursuant to this chapter.