Section 15. (1) The assessment shall be made upon the income accruing to the person during the year ending on th

15. (1) The assessment shall be made upon the income accruing to the person during the year ending on the day on which his accounts have been last made up, or, if his accounts have not been made up within the year ending on the thirty-first day of March in the year immediately preceding that for which the assessment is to be made, then upon the income accruing to him during the year ending on the said thirty-first day of March. (2) In the case of a person for the first time becoming chargeable under Part IV within the year for which the assessment is to be made, or within the year next before that year, the assessment shall be made according to an average of his income for such period as the Collector, having regard to the circumstances, directs.