Section 56A. The fiscal year of all cities of the commonwealth shall begin with July first and end with the following June thirtieth, notwithstanding the provisions of their respective charters, and the returns made to the director under section forty-three shall show the financial condition of the city at the close of business on June thirtieth; provided, however, that the treasurer shall, until July fifteenth, enter in the books all items for the payment of bills incurred and the salaries and wages earned during the previous fiscal year, excepting payment of school teachers’ salaries which have been deferred under the provisions of section forty of chapter seventy-one, and the expenditures therefor shall be deemed to be as of June thirtieth preceding.