TDS on investment fund distributions requires payers to deduct tax when income is credited or paid, with resident and non resident rules. The payer must deduct tax at source on income payable to unit holders of specified investment funds at the time such income is credited to the payee's account or paid, with separate withholding rules for resident and non resident payees and a proviso that no deduction is made where income payable to non residents is not chargeable under the Act; amounts credited to suspense or similarly named accounts are deemed to be credited to the payee for this purpose, and 'unit' is defined by reference to the Explanation to section 115UB.