Deduction under Chapter VIA Part C requires timely return filing; failure to file bars claim of these deductions. Deductions under Chapter VIA (Part C) are not allowable unless the assessee furnishes a return of income on or before the due date; this rule applied to specified incentive deductions for assessment years from 2006 and was broadened by substitution effective 2018 to cover deductions under the Chapter headed 'C. Deductions in respect of certain incomes.' Administrative circulars address limited condonation of delayed returns claiming specified deductions under the executive condonation mechanism.