(10) Where a registered dealer sells goods and the price charged for the goods is expressed not to include an amount of tax payable under this Act the amount may be refunded to the seller or may be applied by the seller under clause (b) of sub-section (3) of this section without the seller being required to refund an amount to the purchaser. (11) Notwithstanding anything contained to the contrary in sub- section (3) of this section, no refund shall be allowed to a dealer who has not filed any return due under this Act.” 7. Sub-section (1) provides that any amount of tax, penalty and interest that is in excess of the amount due from a person shall be refunded to him by the Commissioner. Sub-section (2) permits the Commissioner to first apply such excess to recover any other amount that is due under the Act or the Central Sales Tax Act, 1956. Sub-section (3), which is relevant for our purpose, provides the assessee with the option of getting the refund or carrying it forward to the next