Section 12. Re-opening of assessment at the instance of the assessee.

(1) Where an assessee assessed under section 11 makes an application to the Income-tax Officer, within one month from the date of service of a notice of demand issued in consequence of the assessment, for the cancellation of the assessment on the ground-- (i) that he was prevented by sufficient cause from making the return required under sub-section (2) of section 8, or (ii) that he did not receive the notice issued under sub-section (1) of section 10, or (iii) that he had not a reasonable opportunity to comply, or was prevented by sufficient cause from complying, with the terms of the notice referred to in clause (ii), the Income-tax Officer shall, if satisfied about the existence of such ground, cancel the assessment and proceed to make a fresh assessment in accordance with the provisions of section 10 or section 11. (2) Every application made under sub-section (1) shall be disposed of within ninety days from the date of receipt thereof by the Income-tax Officer: Provided that in computing the period of ninety days aforesaid, any delay in disposing of the application which is attributable to the assessee shall be excluded.