35CCB. (1) Where an assessee incurs any expenditure on or before the 31st day of March, 2002 by way of payment of any sum—
(a) to an association or institution, which has as its object the undertaking of any programme of conservation of natural resources or of afforestation, to be used for carrying out any programme of conservation of natural resources or afforestation approved by the prescribed authority85; or
(b) to such fund for afforestation as may be notified by the Central Government,
the assessee shall, subject to the provisions of sub-section (2), be allowed a deduction of the amount of such expenditure incurred during the previous year.
(2) The deduction under clause (a) of sub-section (1) shall not be allowed with respect to expenditure by way of payment of any sum to any association or institution, unless such association or institution is for the time being approved in this behalf by the prescribed authority86 :
Provided that the prescribed authority shall not grant such approval for more than three years at a time.
(3) Where a deduction under this section is claimed and allowed for any assessment year in respect of any expenditure referred to in sub-section (1), deduction shall not be allowed in respect of such expenditure under any other provision of this Act for the same or any other assessment year.