Montana Title 1. General Laws and Definitions § 1-2-201. Statutes--effective date

(1)(a) Except as provided in subsection (1)(b), (1)(c), or (1)(d), every statute adopted after January 1, 1981, takes effect on the first day of October following its passage and approval unless a different time is prescribed in the enacting legislation.

(b) Subject to subsection (1)(d), every statute providing for appropriation by the legislature for public funds for a public purpose takes effect on the first day of July following its passage and approval unless a different time is prescribed in the enacting legislation.

(c) Subject to subsection (1)(d), every statute providing for the taxation of or the imposition of a fee on motor vehicles takes effect on the first day of January following its passage and approval unless a different time is prescribed in the enacting legislation.

(d) Every statute enacted during a special session of the legislature takes effect upon passage and approval unless a different time is prescribed in the enacting legislation.