A look at the Income-tax Act, 1961, post amendment by the Finance Act, 2021, makes it clear that the amendment to Section 148 has been made from 1-4-2021. This clearly implies that from 1-4-20201, the amended Section 148 shall come into force. The extension of date for issue of notice u/s 148 is only an extension of limitation. It cannot over-ride a substantive amendment in procedural law. The Provisions of Section 148 shall have to be read in their amended form from 1-04-2021 in the absence of a saving clause for the older procedure envisaged by Section 148 in its pre-amended form. A considered view can therefore be taken that a notice on 1-4-2021 is liable to the new procedure envisaged by Section 148A and the amended Section 148 as read with the other amended / inserted provisions regarding reassessment as made by the Finance Act, 2021, in the Income-tax Act, 1961. There is a possibility that this issue may see substantial litigation in the near future, especially in the form or writ petitions before the High Court. As this question has been answered for educational purposes, you are requested to obtain proper legal advice based upon the facts and circumstances of your case by a tax professional of your choice.