Wash. Rev. Code § 91.08.430
The owner of any lands assessed under this chapter may at any time after the time fixed by the treasurer's notice for payment without interest, discharge his or her lands from the unpaid assessment by paying the principal of all installments unpaid with interest thereon at a rate determined by the board to the next anniversary of the time fixed as aforesaid; or he or she may pay one or more installments, with like interest, beginning with installment number ten and continuing in the inverse numerical order of installments. The successor in title to any part of his or her lands may have the proportionate assessment segregated on the roll and charged to such part upon his or her producing to the treasurer his or her recorded deed to such part.
RCW 91.08.430