Penalty for concealment of income: procedural initiation, tracing of unpenalised earlier additions, and deemed concealment after search. Penalty for concealment of income prescribes who may levy penalty, the timing and initiation by show cause notice, and that penalty is additional to tax. Additions on questions of law or debatable issues do not attract penalty, whereas failures to explain, false or unsubstantiated explanations, or non disclosure may. Explanation 2 permits treating current year receipts traced to earlier unpenalised additions as concealed income of the earlier year, allowing penalty initiation notwithstanding completion of earlier proceedings. A search-triggered deeming provision treats undisclosed pre-search assets or entries as concealed even if declared later.