Unless the occupant claims under an official deed given either to the occupant or those under whom the occupant claims, as hereinbefore provided, or under an entry in the land office of the United States, or the official certificate, duplicate or receipt thereof, or unless the claimant has had notice, actual or constructive, of the occupant’s possession, the claimant may, within 30 days after entry of judgment on the verdict or findings in the claimant’s favor, serve upon the occupant a written demand that within one year the occupant pay the claimant the sum assessed as the value of the land without the improvements, less the taxes and assessments paid thereon as aforesaid, with interest as aforesaid. Such demand shall be served, and the service proved, as in the case of a summons, and shall then be filed with the court administrator. If the occupant does not within one year after such service pay into court the amount so demanded, the occupant shall forfeit all claim to compensation, and execution may then issue for the possession of the land; but, if the occupant do so pay, the court shall by judgment confirm the title in the occupant.