Mont. Code § 32-2-943
A mutual association and a federal savings association incorporated or organized under the laws of the United States or a federal reserve bank may, at its election, remain closed and refrain from the transaction of business on Saturdays. Any Saturday on which a mutual association remains closed is, with respect to the mutual association, a holiday and not a business day. Any act authorized, required, or permitted to be performed on a Saturday at or by or with respect to a mutual association, including any federal savings association or federal reserve bank, may be performed on the next succeeding business days, and no liability or loss of any rights of any kind will result from such closing on Saturday or from the nonopening of any mutual association for the transaction of business on any Saturday under the authority of 32-2-943 through 32-2-945.
§ 32-2-943, MCA