Where a dealer makes sales of taxable goods in kolkata SARAS-2010, a national level fair, to be held at Salt Lake City, Kolkata, from the 9th day of December, 2010 to the 20th day of December, 2010, such dealer may, for the purpose of determination of his turnover of sales on which tax is payable, deduct under clause (c) of sub-section (1) of section 16 from his turnover of sales, that part of his turnover of sales which represents such sales of taxable goods, and such dealer shall on demand by the appropriate authority under the Act, furnish the relevant tax invoice or invoice or cash memo or bill as the case may be :

Provided that no such deduction shall be allowed unless the dealer selling the goods, on demand by the appropriate authority under the Act, furnishes the relevant tax invoice or invoice or cash memo or bill.