When a piece of legislation is yet to be passed as a law by the Houses of Parliament, it is termed a Bill. A Finance Bill is a Bill that, as the name suggests, concerns the country's finances — it could be about taxes, government expenditures, government borrowings, revenues, etc. Since the Union Budget deals with these things, it is passed as a Finance Bill.
Rule 219 of the Rules of Procedure of Lok Sabha states: ‘Finance Bill’ means the Bill ordinarily introduced in each year to give effect to the financial proposals of the Government of India for the following financial year and includes a Bill to give effect to supplementary financial proposals for any period.
There are different kinds of Finance Bills — the most important of them is the Money Bill. The Money Bill is concretely defined in Article 110. A Money Bill is certified by the Speaker as such — in other words, only those Financial Bills that carry the Speaker’s certification are Money Bills.
Article 110 states that a Bill shall be deemed to be a Money Bill if it contains only provisions dealing with all or any of the following matters:
(a) the imposition, abolition, remission, alteration or regulation of any tax;
(b) the regulation of the borrowing of money or the giving of any guarantee by the Government of India, or the amendment of the law with respect to any financial obligations undertaken or to be undertaken by the Government of India;
(c) the custody of the consolidated Fund or the Contingency Fund of India, the payment of moneys into or the withdrawal of moneys from any such Fund;
(d) the appropriation of moneys out of the consolidated Fund of India;
(e) the declaring of any expenditure to be expenditure charged on the Consolidated Fund of India or the increasing of the amount of any such expenditure;
(f) the receipt of money on account of the Consolidated Fund of India or the public account of India or the custody or issue of such money or the audit of the accounts of the Union or of a State; or
(g) any matter incidental to any of the matters specified in sub clause (a) to (f)
A Bill shall not be deemed to be a Money Bill by reason only that it provides for the imposition of fines or other pecuniary penalties, or for the demand or payment of fees for licences or fees for services rendered, or by reason that it provides for the imposition, abolition, remission, alteration or regulation of any tax by any local authority or body for local purposes
If any question arises whether a Bill is a Money Bill or not, the decision of the Speaker of the House of the People thereon shall be final
There shall be endorsement of every Money Bill when it is transmitted to the Council of States under Article 109, and when it is presented to the President for assent under Article 111, the certificate of the Speaker of the House of the People signed by him that it is a Money Bill.

Read full Finance Bill documents

Finance Bill 2020