34. Limitation on assessment and re-assessment.- (1) No assessment or re-assessment under section 32 of this Act shall be made by the Commissioner after the expiry of four years from
(a) the date on which the person furnished a return under section 26 or sub-section (1) of section 28 of this Act; or
(b) the date on which the Commissioner made an assessment of tax for the tax period, whichever is the earlier:
PROVIDED that where the Commissioner has reason to believe that tax was not paid by reason of concealment, omission or failure to disclose fully material particulars on the part of the person, the said period shall stand extended to six years.
(2) Notwithstanding sub-section (1) of this section, the Commissioner may make an assessment of tax within one year after the date of any decision of the Appellate Tribunal or court where the assessment is required to be made in consequence of, or to give effect to, the decision of the Appellate Tribunal or court which requires the re-assessment of the person.