The primary duty of the Finance Commission of India is

The correct answer is A. The Finance Commission is set up under Article 280 every five years, or earlier if needed. Its core job is to recommend how the net proceeds of Union taxes are shared between the Centre and the States, and how the States' share is divided among themselves. It also suggests grants-in-aid under Article 275 and measures to augment the State Consolidated Funds. The 15th Finance Commission covered 2021-26, and the 16th was constituted in late 2023 for 2026-31.

Why the others are wrong:

• B is wrong because the Union Budget is prepared by the Ministry of Finance (Department of Economic Affairs and the Budget division) and presented under Article 112.
• C is wrong because the Commission does not advise the President on financial matters in general. Its role is limited to the specific devolution and grants questions referred to it, and its recommendations are not binding.
• D is wrong because allocation to ministries is a matter of budgetary appropriation by Parliament, handled by the Ministry of Finance and the Department of Expenditure. Earlier, plan allocations were done by the Planning Commission, which was replaced by NITI Aayog in 2015.

Core concept: vertical and horizontal fiscal devolution, which is central to cooperative federalism and frequently comes up in Mains GS-II and GS-III answers on centre-state finances.

Trap: aspirants often treat the Finance Commission as a budget-making or allocation body, or assume its recommendations are binding. They are advisory, and the President accepts them with a memorandum to Parliament.