Under-reported income penalty: section 270A sets computation rules, exclusions, and higher punishment for misreporting. Penalty under section 270A applies to under-reported income and is imposed during assessment or appellate proceedings. Under-reported income is computed by comparing assessed, reassessed or deemed total income with returned or previously assessed income, including first-time assessments, non-filing cases, reassessment, MAT/AMT situations, and loss-to-income conversions. The provision excludes bona-fide explanations, certain estimates, transfer pricing cases with proper disclosures, and search-related undisclosed income covered by section 271AAB. Penalty is 50% of tax payable for under-reporting and 200% where misreporting is involved.