The Council shall approve the budget for each succeeding fiscal year not later than the first Monday in June. The expenditure authorizations shall be summarized and approved in accordance with appropriate activity centers consistent with State requirements. Each activity center shall show an estimate of expenditures by object codes prescribed by the Michigan Department of Treasury. In its approving resolution, the Council shall also determine the amount to be raised by tax upon real and personal property for City purposes. The levy shall not exceed 18 mills of the taxable value of all real and personal property subject to taxation in the City. Not less than 10% of the total levy herein shall be reserved in a fund restricted for capital improvements. In no case shall Council increase the total tax rate of the City by more than 1 mill over the total mills levied during the immediately preceding year.