(i) A state legislature can impose taxes on professions, trades, callings and employments. But, the total amount of such taxes payable by any person should not exceed ₹2,500 per annum. (ii) A state legislature is prohibited from imposing a tax on the supply of goods or services or both in the following two cases: (a) where such supply takes place outside the state; and (b) where such supply takes place in the course of import or export. (iii) A state legislature can impose tax on the consumption or sale of electricity. But, no tax can be imposed on the consumption or sale of electricity which is (a) consumed by the Centre or sold to the Centre; or (b) consumed in the construction, maintenance or operation of any railway by the Centre or by the concerned railway company or sold to the Centre or the railway company for the same purpose. (iv) A state legislature can impose a tax in respect of any water or electricity stored, generated, consumed, distributed or sold by any authority established by Parliament for regulating or developing any inter-state river or river valley. But, such a law, to be effective, should be reserved for the president’s consideration and receive his/her assent.