From the effective date of the budget, the several amounts stated therein as proposed expenditures shall be and become appropriated to the several departments, offices, and agencies for the respective objects and purposes therein named. All appropriations shall lapse at the end of the fiscal year to the extent that they shall not have been expended or lawfully encumbered except appropriations for specific capital projects incomplete at the end of the fiscal year. At any meeting after the adoption of the budget, the City Council may amend or supplement the budget by motion adopted by an affirmative four-fifths vote.