Mont. Code Ann. § 7-12-4304

At any time within 15 days after the date of the first publication of the notice of passage of the resolution of intention, an owner of property liable to be assessed for the work may make written protest against the proposed work or against the extent or creation of the district to be assessed, or both. The notice must be in writing and be delivered to the clerk of the city council, who shall endorse on the notice the date of receipt.