The primary function of the Finance Commission in India is to

1. The Finance Commission is a constitutional body (Article 280) set up by the President of India every five years. 2. Its primary function, as mandated by the Constitution, is to make recommendations regarding the distribution of net proceeds of taxes between the Union (Centre) and the States (vertical devolution) and the allocation of the States' share among the States themselves (horizontal distribution). 3. Preparing the Annual Budget (B) is the function of the Finance Ministry. 4. While the Commission advises the President on financial matters specified in its terms of reference (C), its core mandated role is revenue distribution. 5. Allocating funds to specific ministries (D) is part of the budgetary process, not the Finance Commission's primary role. 6. Therefore, distributing revenue between the Centre and States is its primary function.