Wash. Rev. Code § 30A.20.060
A bank shall repay all deposits to the depositor or his or her lawful representative when required at such time or times and with such interest as the regulations of the corporation shall prescribe. These regulations shall be prescribed by the directors of the bank and may contain provisions with respect to the terms and conditions upon which any account or deposit will be maintained by the bank. These regulations and any amendments shall be available to depositors on request, and shall be posted in a conspicuous place in the principal office and each branch in this state or, if the regulations and any amendments are not so posted, a description of changes in the regulations after an account is opened shall be mailed to depositors pursuant to 12 U.S.C. Sec. 4305(c) or otherwise. All these rules and regulations and all amendments shall be binding upon all depositors. At the option of the bank, a passbook shall be issued to each savings account depositor, or a record maintained in lieu of a passbook. A deposit contract may be adopted by the bank in lieu of or in addition to account rules and regulations and shall be enforceable and amendable in the same manner as account rules and regulations or as provided in the deposit contract. A copy of the contract shall be provided to the depositor.
RCW 30A.20.060