The governing authorities shall at all times keep within the sums named in their said budget and within the annual revenue, always seeking to lessen expenditures instead of exceeding revenue and budget estimates. There shall not be added to the amount to be appropriated and authorized to be expended for any item, or to the total amount appropriated and authorized to be expended from any fund any amount or percentage whatever because of any anticipated loss of revenue by reason of the nonpayment of taxes levied for the current fiscal year. The amount appropriated and authorized to be expended for any item contained in such budget, except for capital outlay, election expenses, and payment of emergency warrants and interest thereon, must not exceed the amount actually estimated for such item, and the total amount appropriated and authorized to be expended from any fund, except for capital outlay, election expenses and payment of emergency warrants and interest thereon, shall not exceed the total amount actually estimated for all purposes. The total expenditures authorized to be made from any fund shall not exceed the aggregate cash balance, in such fund at the close of the fiscal year immediately preceding, plus the amount of estimated revenues to accrue to such fund, as determined and fixed in the manner provided by this chapter, and the amount which may be raised for such fund by a lawful tax levy during the current fiscal year. Nothing herein contained shall be construed to prevent any municipality from making adequate provision at any time for the payment of principal of and interest on its outstanding bonded indebtedness.