On or before June 1 in each year the City Manager shall submit to the Council a tax budget for the ensuing fiscal year. For that purpose, at such date as he shall deter-mine, he shall obtain from the head of each department or agency of the City, plans for the work to be undertaken by such agency during the next fiscal year together with estimates of the cost of performing such work. The Department of Finance shall supply estimates of available revenue. From these data the City Manager shall prepare the consolidated estimates for the annual tax budget. The Council shall consider these estimates and adopt them, with or without amendments, as the tax budget of the City for the ensuing year, and transmit them, on. or before July 15 to the County Budget Commission, in the form required by law.