and it was held in Commissioner of Sales Tax, Uttar Pradesh vs The Modi Sugar Mills Ltd. (1) that the assessee who had (1) ; 551 elected to submit his return on the turnover of the previous year was liable to be assessed to sales tax at the rate force on the first day of the year of assessment because the liability arose on that date, and any subsequent enhance ment of the rate by the notification under section 3 A did not alter the liability, The Legislature however passed the Amending Act and inserted the following as section 31, "31(1) Where any dealer has, in accord ance with the provisions of Section 7, as it stood prior to its amendment by Section 7 of U.P. Act XIX of 1956, opted to be assessed to tax on the basis of his turnover of the previ ous year, he shall be assessed to tax at such rates as are prevalent during the year for which the assessment is being made, and if the rates of tax on any goods or class of goods are altered during such assessment year, the dealer, in respect of the turnover of such goods, shall be liable to pay tax at the altered rates, as if the altered rates were in force during the previous year also propor tionately for the same number of days as they are in force during the assessment year.