Wash. Rev. Code § 11.140.160
(1) Except as provided in subsection (3) of this section, unless previously barred by adjudication, consent, or limitation, a claim for relief against a custodial trustee for accounting or breach of duty is barred as to a beneficiary, a person to whom custodial trust property is to be paid or delivered, or the legal representative of an incapacitated or deceased beneficiary or payee:
(3) A claim for relief is not barred by this section if the claimant:
(b) Is an incapacitated adult, until the earliest of two years after:
[ 2025 c 111 s 16.]