That the corporate authorities of any such sanitary district which heretofore or shall hereafter have funds on hand derived from taxes levied for the payment of interest on interest coupons which were not paid when due, and said funds are no longer needed for such purpose, then the corporate authorities of such sanitary district at anytime without regard to the annual appropriation ordinance may appropriate and use such funds for the purpose of paying interest coupons of said sanitary district and shall reduce the tax levy for interest on bonds in the amount and at the time such funds on hand are so used.
70 ILCS 2605/9a