In order to run the state, the government needs money. The state incurs expenses for the activities it undertakes. In order to pay for these expenses, it must raise and generate income.
In democracy, the government cannot undertake activities, incur expenses or raise incomes without the approval of elected representatives in the constituted body. This approval can be obtained only when the government prepares and presents the budget to the elected body.
In India, such permission the government take from the Lok Sabha, State legislative assembly, Municipal bodies and Panchayats.