Mont. Code Ann. § 31-1-306

No assignment of wages or salary to a wage broker by a married person who shall have a spouse residing in this state shall be valid or enforceable without the consent of such spouse, evidenced by the spouse's signature to said assignment, executed and acknowledged before a notary public or other officer empowered to take acknowledgments. No wage broker or person connected with a wage broker, directly or indirectly, shall be authorized to take any such acknowledgments.