Wash. Rev. Code § 36.70A.600
(1) A city planning pursuant to RCW 36.70A.040 is encouraged to take the following actions in order to increase its residential building capacity:
(x) Develop a local program that offers homeowners a combination of financing, design, permitting, or construction support to build accessory dwelling units. A city may condition this program on a requirement to provide the unit for affordable homeownership or rent the accessory dwelling unit for a defined period of time to either tenants in a housing subsidy program as defined in RCW 43.31.605(14) or to tenants whose income is less than eighty percent of the city or county median family income. If the city includes an affordability requirement under the program, it must provide additional incentives, such as:
(y) Develop a local program that offers homeowners a combination of financing, design, permitting, or construction support to convert a single-family home into a duplex, triplex, or quadplex where those housing types are authorized. A local government may condition this program on a requirement to provide a certain number of units for affordable homeownership or to rent a certain number of the newly created units for a defined period of time to either tenants in a housing subsidy program as defined in RCW 43.31.605(14) or to tenants whose income is less than eighty percent of the city or county median family income. If the city includes an affordability requirement, it must provide additional incentives, such as:
(2) A city planning pursuant to RCW 36.70A.040 may adopt a housing action plan as described in this subsection. The goal of any such housing plan must be to encourage construction of additional affordable and market rate housing in a greater variety of housing types and at prices that are accessible to a greater variety of incomes, including strategies aimed at the for-profit single-family home market. A housing action plan may utilize data compiled pursuant to RCW 36.70A.610. The housing action plan should:
[ 2022 c 246 s 1; 2020 c 173 s 1; 2019 c 348 s 1.]