the amount calculated with respect to that national tax, according to the period after the enforcement of this Act (if the day following the day on which 10 days have elapsed counting from the day on which the letter of demand was issued falls after the enforcement of this Act, the period on and after that day), in accordance with the calculation of the amount of delinquency additional tax to be collected under the provisions of the former tax laws (the provisions of the former tax laws concerning the simplified delinquency additional tax table are not to be applied, and the rate used in calculating that amount is to be two sen per day for every 100 yen of the amount of national tax that forms the basis of the calculation).