Assessment in case of special circumstances

(1) Assessment in case of Price Variation-- Where a dealer receives in any year any amount due to price variation which would have been in his turnover for any previous tax period if it had been received by him during that period, it shall be deemed to be turnover during the tax period in which such amount was received and he shall, during the tax period in which such amount was received, include such amount in the return separately for the tax period, to the assessing authority and the assessing authority shall assess the tax payable on such amount as his turnover for the tax period in which such amount is received: