The recent 2G-controversy and the related debate over the role of the PAC as opposed to the JPC also raises a broader Issue regarding the general scrutiny of government finances by Parliament. Oversight of the government’s finances involves the scrutiny of the government’s financial proposals and policies. The Indian Constitution vests this power with the Parliament by providing that (a) taxes cannot be imposed or collected without the authority of law, and (b) expenditure cannot be incurred without the authorisation of the legislature. The Indian Parliament exercises financial oversight over the government budget in two stages: (1) at the time of presentation of the annual budget, and (2) reviewing the government’s budget implementation efforts through the year. The Parliament scrutinises the annual budget (a) on the floor of the House, and (b) by the departmentally related standing committees. Scrutiny on the floor of the House The main scrutiny of the budget in the Lok Sabha takes place through: (a) General discussion and voting: The general discussion on the Budget is held on a day subsequent to the presentation of the Budget by the Finance Minister. Discussion at this stage is confined to the general examination of the Budget and policies of taxation expressed during the budget speech. (b) Discussion on Demand for Grants: The general discussion is followed by a discussion on the Demand for Grants of different ministries. A certain number of days or hours are allocated for the discussion of all the demands. However, not all the demands are discussed within the allotted number of days. The remaining undiscussed demands are disposed of by the Speaker after the agreement of the House. This process is known as the ‘Guillotine’. Figure 1 shows the number of Demands discussed and guillotined over the last five years. It shows that nearly 90% of the Demands are not discussed every year. 
Some Important Budget Documents Annual Financial Statement – Statement of the estimated receipts and expenditure of the government. Demand for Grants –Expenditure required to be voted by the Lok Sabha. A separate Demand is required to be presented for each department of the government. Supplementary Demand for Grants – Presented when (a) authorized amounts are insufficient, or (b) need for additional expenditure has arisen. Finance Bill – Details the imposition of taxes, the rates of taxation, and its regulation. Detailed Demand for Grants – Prepared on the basis of the Demand for Grants. These show further break-up of objects by expenditure, and also actual expenditure in the previous year. For more details see detailed note on Financial Oversight by Parliament here.
The presentation of the Annual Budget before the parliament is one of the mechanisms available to any legislature to scrutinise and authorise revenues and expenditures of the country. In this post I quote and summarise from two sources (Rick Stapenhurst, "The legislature and the Budget", in Legislative Oversight and Budgeting, World Bank Institute Development Studies, and The evolution of parliament’s power of the purse) which describe briefly how oversight by the legislature over the state's finances evolved historically. "The evolution of legislative "power of the purse" dates back to medieval times, when knights and burgesses in England were summoned to confirm the assent of local communities to the raising of additional taxes." By the 1300s the English parliament had begun to use its power to vote on funds depending on the acceptance of petitions presented by parliament to the monarch. In 1341, the monarch agreed that citizens should not be taxed ("charged or grieved to make common aid or sustain charge") without the assent of Parliament. "In parallel, the English Parliament began to take an interest in how money was collected, as well as how it was spent." In the 1300's itself, it started appointing commissioners to audit the accounts of tax collectors. This power of oversight however evolved gradually, and particularly over the 16th century, when the "monarchs needed parliamentary support and voting of funds for their various political and religious battles. King Henry VIII for example, gave Parliament enhanced status in policy making, in return for support during his battles with Rome." The 1689 Bill of Rights firmly established "the principle that only Parliament could authorize taxation. Still, at this stage there was still no such thing as an annual budget, and there was no comprehensive control of expenditures." The British Parliament also passed a resolution in 1713 to limit Parliament's power to "not vote sums in excess of the Government’s estimates. Consequently, the only amendments that are in order are those which aim to reduce the sums requested." "Since that time, the "power of the purse" function has been performed by legislatures around the world as a means to expand their democratic leverage on behalf of citizens."
