Wash. Rev. Code § 35.45.065
The city or town council may provide by ordinance that all or part of the interest upon said bonds shall be paid from the general revenues of the city or town and may create a local improvement district bond interest fund for this purpose. If the city or town council determine that the city or town shall pay all interest on such bonds from its general revenues, the interest coupons attached to the bond shall recite that the interest thereby evidenced is payable from general revenues. If the city or town council determines that the city or town council shall pay a part of the interest on such bonds from its general revenues, the interest coupons representing interest payable from the general revenues of the city or town shall be denominated as "B" coupons and shall recite that the interest payable thereunder is payable from the general revenues of the city or town.
RCW 35.45.065