(2)The deduction under [clause (a)] [Inserted by Act 12 of 1990, Section 12 (w.e.f. 1.4.1991).] 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 authority:Provided that the prescribed authority shall not grant such approval for more than three years at a time.
