On 1 April 2026, the Income-tax Act, 2025 replaced the 1961 Act. The numbering is new, the structure is tighter, and the conceptual architecture has shifted — most visibly in the disappearance of 'previous year' and 'assessment year' in favour of a single 'tax year'. A reading of what has actually changed, what is structural cosmetic, and what the bar needs to know for its first cycle of tax-year-2026-27 work.