(2)Whenever the [Commissioner of the Corporation] has made any payment to the Accountant-General under sub-section (1), the [State Government] shall reimburse the Corporation out of the rents and income attached under that sub-section, and if such rents and income prove insufficient for that purpose the Corporation may , with the previous sanction of the [State Government] increase the maximum authorized by [section 165 of the Calcutta Municipal Act, 1951], to such extent as may be necessary for the purpose of making up the deficiency:Provided that no such increase shall be made, unless the taxes imposed by sections 83 and 84 are levied at the maximum rates respectively prescribed by those section.