Assuming any required preliminary notice was given, a Minnesota mechanic’s lien ceases at the end of 120 days after doing the last of the work, or furnishing the last item of skill, material, or machinery, unless within this period:

(1) a statement of the claim is filed for record with the county recorder or, if registered land, with the registrar of titles of the county in which the improved premises are situated, or, if the claim is made under section Minn. Stat. § 514.04, with the secretary of state; and

(2) a copy of the statement is served personally or by certified mail on the owner or the owner’s authorized agent or the person who entered into the contract with the contractor.

More information about Minnesota’s mechanic’s lien filing requirements can be found at Minn. Stat. § 514.08 and in Minn. Stat. Chapter 514.