No claim shall be allowed against the estate of a ward upon application of the claimant unless it shall be in writing, filed in duplicate with the clerk, stating the claimant’s name and address, and describing the nature and the amount thereof, if ascertainable. It shall be accompanied by the affidavit of the claimant, or of someone for the claimant, that the amount is justly due, or if not due, when it will or may become due, that no payments have been made thereon which are not credited, and that there are no offsets to the same, to the knowledge of the affiant, except as therein stated. The duplicate of said claim shall be mailed by the clerk to the conservator or the conservator’s attorney of record; however, valid contract claims arising in the ordinary course of the conduct of the business or affairs of the ward by the conservator may be paid by the conservator without requiring affidavit or filing.