Construction lien is a claim upon property for money owed to a contractor, material supplier or anyone who supplied labor or materials for improvements to the property.  Every state permits a person who supplies labor or materials for a construction project to claim a lien against the improved property.  While some states differ in their definition of improvements, some states limit lien claims to buildings or structures.  Most states permit the filing of a document with the local court that puts parties interested in the property on notice that the party asserting the lien has a claim.  States differ widely in the method and time within which a party may act on their lien.