Return of loss filing deadline affects carry forward entitlement; late filing may be condoned for genuine hardship. Return of loss for business/profession or capital gains must be filed within the due date to claim carry forward; business loss, speculation loss, capital loss and racehorse loss cannot be carried forward if the return is late and disentitlement applies when the original return was not timely filed. Delay may be condoned administratively in genuine hardship within delegated monetary limits. Exceptions: unabsorbed depreciation can be carried forward despite late filing; losses disclosed only in response to assessment notice are not carry forwardable except house property; previously timely filed assessed losses remain carryable.