(2)The proceedings initiated under section 279 shall be dropped on a claim made by the assessee and on his showing to the effect that—(a)the assessee had been assessed on an amount not lower than what he would be rightly liable for, even if the income alleged to have escaped assessment had been taken into account, or the assessment or computation had been properly made; and(b)he has not impugned any part of the original assessment order for the relevant tax year under section 356 or 357 or 378.