Court held that where no return was filed, it was incumbent on the part of the Assistant Commissioner or the jurisdictional Assessing Officer to have issued a notice under section 148 of the Act to the assessee within the time prescribed under the Act, in which case, the question of the assessee filing an application before the Principal Commissioner under section 119 of the Act would not have arisen at all. Where the law mandates a particular thing to be done in a particular manner, it is incumbent on the part of the Income-tax authorities to follow such procedure. Failure to issue a notice under section 148 of the Income-tax Act, 1961 cannot be to the prejudice of the assessee, if ultimately it is found that the assessee was entitled to a refund. The respondents were directed to examine the refund claim independently and pass appropriate orders within a period of three months from the date of receipt of a copy of this order. (AY.2011-12)