Onus to prove genuineness of transaction not discharged if it wasn't challenged earlier; sec. 68 add

IT-I : Mere fact that certain credit balance appearing in previous years' books of account remained unchallenged, did not shift burden of assessee of proving genuineness of said credit and, therefore, in case of failure of assessee to establish same, amount in question could be added to assessee's taxable income under section 68