If the application to become a domestic mutual association is granted, the director of financial institutions shall require the applicant to enter into an agreement or undertaking with the director, as trustee for the members of the association, to make such cash contributions to an expense fund of the mutual association as in the director's judgment will be necessary then and from time to time thereafter to pay the operating expenses of the association if its earnings should not be sufficient to pay the same in addition to the payment of such dividends as may be declared and credited to members from its earnings.