Penalty for concealment of income governs graded sanctions based on admission, substantiation and timely tax compliance. A special penalty provision imposes graded penalties in addition to tax and interest for undisclosed income found in searches under section 132, with bands tied to the assessee's admission, substantiation, tax payment and return filing by the specified date. The provision defines specified previous year and undisclosed income, excludes certain other penalties in respect of the same undisclosed income, and makes relevant procedural penalty provisions applicable.