And you thought this was a simple question!
You can read all the lien laws in Chapter 514 of the MN Code.
The contractor has to give you written notice of his right to assert a lien in the contract or within 10 days of agreeing to do the work (not of starting the work). 514.011. Failure to give notice means the contractor cannot assert a lien. 514.011.
After giving proper notice at the start of the contract, the contractor has 120 days to perfect the lien. A properly perfected lien must be enforced within 15 years or it expires. 541.03
Any other questions?
Tracey
514.08 Subdivision 1. Notice required. The 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 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.
------------------
This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.