27. (1) Every such contract shall be made on behalf of the Kartripakkha by the Chairman: Provided that a contract involving an expenditure exceeding five lakhs of taka shall not be made by the Chairman without the previous sanction of the Kartripakkha. (2) Every estimate for the expenditure of any sum for carrying out any of the purposes of this Act shall be subject to the approval of the authority who is empowered by sub-section (1) to make or sanction the making of a contract involving the expenditure of a like sum. (3) Sub-sections (1) and (2) shall apply to every variation or abandonment of a contract or estimate, as well as to an original contract or estimate.