Section 39(3) in The Taxation Laws (Amendment) Act, 2006
(3)For the purposes of sub- section (1), the Central Government shall have and shall be deemed to have the power to make rules with retrospective effect as if the Central Government had the power to make rules under section 37 of the Central Excise Act, retrospectively, at all material times. Explanation.- For the removal of doubts, it is hereby declared that no act or omission on the part of any person shall be punishable as an offence, which would not have been so punishable if this section had not come into force.
