Idaho Code § 50-1829
Any suit, action or proceeding which may be commenced for the purpose of determining the validity of the sale of land for assessments, as in this act provided, to quiet title against the same or to remove the cloud thereof or to recover possession from the purchaser in possession of the lands so sold or its or his successor or assign, whether bought by the original owner or his successor in interest, shall be commenced within two (2) years from the date of the expiration of the period of redemption allowed by this act and not otherwise. In every action, suit or proceeding brought for such purposes, whether before or after the issuance of tax deed, the person claiming to be the owner, as against the person claiming under said tax deed, shall tender in the action, suit or proceeding and pay into the court at the time of filing the same amount of the purchase price for which the lands were sold together with all taxes and assessments which have been paid by the purchaser of said land after tax sale together with interest thereon at the rate of eight per cent (8%), per annum from the respective time of payment of such sum or sums up to the time of filing such pleading in the action, suit or proceeding. Said sum or such portion thereof as the courts shall find to be just shall be paid by the purchaser, his heirs or assigns, in case the right of title to the purchaser shall fail in such suit, action or proceeding.
Idaho Code § 50-1829