law: 12. Tax wrongfully collected and paid to Central Government or Union territoryGovernment.
  (1) A registered person who has paid the central tax and the Union territory tax on a transaction considered by him to be an intra-State supply, but which is subsequently held to be an inter- State supply, shall be refunded the amount of taxes so paid in such manner and subject to such conditions as may be prescribed.
  (2) A registered person who has paid integrated tax on a transaction considered by him to be an inter- State supply, but which is subsequently held to be an intra-State supply, shall not be required to pay any interest on the amount of the central tax and the Union territory tax payable.