Penalty for contravening section 269ST: equal-to-receipt sanction, imposable by authority now shifted to Assessing Officer. A penalty applies where any sum is received in contravention of section 269ST: the recipient is liable to pay a penalty equal to the amount of such receipt, unless the recipient proves good and sufficient reasons for the contravention. The provision assigns authority to impose the penalty to the Joint Commissioner, with a statutory change providing that on and after the specified operative date the Assessing Officer shall impose the penalty.