Appealable orders before Commissioner (Appeals) allow aggrieved assessee, deductor or collector to challenge specified assessment and penalty orders. The provision permits any aggrieved assessee, deductor or collector to appeal to the Commissioner (Appeals) against a broad catalogue of orders, including assessments, reassessments and recomputations where liability or adjustments are disputed, orders under rectification and agent-status provisions, assessments arising from search or special assessment schemes, and specified penalty and registration-cancellation orders, subject to limited statutory exclusions and exceptions.