Wash. Rev. Code § 39.96.060
(1) Subject to any covenants or agreements applicable to the obligations issued or incurred by the governmental entity, if the governmental entity enters into a payment agreement with respect to those obligations, then it may elect to treat the amounts payable from time to time with respect to those obligations as the amounts payable after giving effect to the payment agreement for the purposes of calculating:
[ 1993 c 273 s 6.]