Section 142[1] of IT Act notice

A company has received a notice under Section 142[1] of the IT Act and appointed a CA firm's partner as their authorised signatory via Power of Attorney. They are seeking guidance on which letterhead the signatory should use for correspondence: the company's, a plain sheet, or the CA firm's. The consensus is that if the CA partner is officially representing the case as an attorney, they should file their authority on stamp paper and not use the appointing company's letterhead.