7. The person registered under the Central Sales Tax Act, 1956 (Central Act No. 74 of 1956), shall be liable to pay VAT under this Act on any sale made by him within the State, irrespective of the fact that he is not liable to pay tax under section 6 of this Act.  However, the provisions of this section shall not apply in case of a person, who deals exclusively in goods declared tax free under section 16.