123. Burden of proof in a proceeding.—

(1) In the case of proving the points at issue of any proceeding before the Commissioner (Appeal) or the Appellate Tribunal, the affidavit submitted by the Commissioner in the prescribed manner shall be treated as a conclusive proof thereof unless the taxpayer may prove otherwise rebutting the contents of such affidavit.

(2) A copy of the notice issued by the Commissioner and other concerned documents shall be attached with such affidavit.