The pledgee of such lease or the mortgagee of such leasehold interest shall, within 30 days after receipt of the pledge agreement or mortgage, file it or a certified copy thereof with the department.
Mont. Code Ann. § 77-6-402, under Pledges and Mortgages of Leasehold Interests.
Mont. Code Ann. § 77-6-402
The pledgee of such lease or the mortgagee of such leasehold interest shall, within 30 days after receipt of the pledge agreement or mortgage, file it or a certified copy thereof with the department.