Retrospective exemption validates prior actions and mandates refunds with a limited claim period following assent. The amendment declares notification No. S.O. 417(E) to be retrospectively effective from 1 March 2002, validating all actions taken under it and treating the Central Government as having retrospectively possessed power to exempt specified goods. It mandates refund of excise duties collected that would not have been due had the exemption applied, sets a one year limit for refund claims from the Finance Bill's assent, and removes criminal liability for acts that would not be offences had the notification been retroactively effective.