Under Article 114(3) of the Constitution, no amount can be withdrawn from the Consolidated Fund without the enactment of such a law by Parliament. After the Demands for Grants are voted by the Lok Sabha, Parliament's approval to the withdrawal from the Consolidated Fund of the amounts so voted and of the amount required to meet the expenditure charged on the Consolidated Fund is sought through the Appropriation Bill.
The whole process beginning with the presentation of the Budget and ending with discussions and voting on the Demands for Grants requires a fairly long time. The Lok Sabha is, therefore, empowered by the Constitution to make any grant in advance in respect of the estimated expenditure for a part of the financial year pending completion of procedure for the voting on the demands. The purpose of the 'Vote on Account' is to keep the government functioning, pending voting of 'final supply'. The Vote on Account is obtained from Parliament through an Appropriation (Vote on Account) Bill.