(3)An appeal shall be presented within thirty days of the following date, that is to say,-(a)where the appeal relates to assessment or penalty or fine, the date of service of the notice of demand relating to the assessment or penalty or fine or(b)in any other case, the date on which the intimation of the order sought to be appealed against is served:Provided that the Appellate Assistant Commissioner may admit an appeal after the expiration of the said period if he is satisfied that the appellant had sufficient cause for not presenting it within that period.
