Failure to Deduct Tax - exemption from being treated as assessee in default where payee files return and pays tax. The amendment provides that a person who fails to deduct tax at source will not be deemed an assessee in default if the resident has filed a return under section 139, taken the sum into account for computing income, paid the tax declared, and the payer furnishes a prescribed certificate from an accountant. If this conditional exemption does not apply, interest runs from the date tax was deductible until the resident furnishes the return. The limitation period in sub section (3)(ii) is extended from four to six years and 'accountant' is defined by reference to section 288(2).