Penalty under section 271(1)(c): not imposed when tax under normal provisions is lower than MAT for pre operative cases. Where tax computed under ordinary provisions is less than tax payable under the deeming provisions for Minimum Alternate Tax, penalty for concealment under section 271(1)(c) cannot be imposed with reference to additions or disallowances made under normal provisions for periods prior to the prospective operative date of the substituted Explanation; if MAT income is adjusted for those periods, penalty applicability depends on the nature of the adjustment, the position extends to analogous MAT provisions, and authorities are directed not to institute or to withdraw appeals on this ground.