Mont. Code Ann. § 70-22-104

A surveyor shall complete, sign, stamp with the surveyor's seal, and file with the county clerk and recorder of the county where the corner is situated a written record of corner establishment or restoration to be known as a "corner record" for every public land survey corner and accessory to the corner that is established, reestablished, monumented, remonumented, restored, rehabilitated, perpetuated, or used as control in any survey by the surveyor and within 90 days after the establishment unless the corner and its accessories are substantially as described in an existing corner record filed in accordance with the provisions of this part.