The Finance Bill is a legal document presented by the Finance Minister before Parliament at the time of presenting the Union Budget. It encapsulates any changes to the taxation policy of the government - and its passage means parliamentary authority to the government to raise funds by taxing Indian entities for the forthcoming financial year, i.e the Bill gives the permission to the government earn through taxes. The government is legally required to present the Finance Bill before Parliament under Article 110 (1) (A) of the Constitution.
This Bill is a Money Bill, and therefore is only introduced in and needs to be approved by the the Lok Sabha, as is constitutionally allowed. After approval of Parliament, the Bill is know as the Finance Act for that year.
All proposed changes to direct taxes, including to Corporate Tax and the closely-watched Income Tax slabs are legislatively passed through the Finance Bill.
Overall, the Bill outlines the taxes the seeks to impose, and provides the legislative facilitation required. Therefore, Bill also carries out appropriate amendments to previous Finance Acts, and applicable Acts of Parliaments such as those governing the Reserve Bank of India, Securities and Exchange Board of India, Goods and Service Tax or financial and economic areas such 'benami' property, money laundering and insurance or to any other area or Act deemed necessary.