Tribunal has been conferred with powers to condone the delay upto 3 months, beyond the period of 3 months or 6 months in case of filing of appeals, where sufficient cause for the delay is shown.
Similarly, delay upto 45 days could be condoned by the Tribunal in filing the
memorandum of cross objections where sufficient cause for the delay is shown.
(ICAI FAQ PUBLICATIONS 06-09-2017 Appeals to the Appellate Tribunal: FAQ NO. 46)