(1)If in any case -(a)on the preparation of the estimate of any year, it appears that the estimated income of the Board for such year, after deducting therefrom the estimated expenditure of such year, will be insufficient for the payment of the interest which may be payable by the Board during such year to Government or to any other creditor and of any sinking fund established under Section 64 and of any sum the repayment of which is due in pursuance of any terms fixed under Section 56 ; or(b)at any time during the course of a year, it appears that the income of such portion of the year as has then elapsed and the estimated income of the residue of such year after deducting therefrom the actual expenditure of such past portion and the estimated expenditure of such residue, will be insufficient for the payment of the said interest, sinking funds and sums due;the Board may, and upon the requisition of Government shall, increase the rates for the time being in force to such extent as will render the estimated income of the year sufficient as nearly as may be for the payment in full of the said interest, sinking funds and sums due.
