The BMA was held to operate prospectively from A.Y. 2016-17,...

The BMA was held to operate prospectively from A.Y. 2016-17, with the proviso to section 3(1) allowing only limited retrospective valuation of an undisclosed asset when it first comes to the AO's notice. An explained inherited corpus and voluntarily disclosed historic interest were not "undisclosed assets" under sections 2(11) and 4(1), so the BMA could not be used to tax them; any pre-2016 income had to be dealt with under the IT Act. The notice under section 10(1) was also jurisdictionally defective because it omitted the relevant year and was issued belatedly. A.Y. 2019-20 was not the correct year of chargeability; at most, the proviso could point to A.Y. 2017-18.