AY 2026-27 vs Tax Year 2026-27: The Dual-Law Income Tax Transition Professionals Must Get Right

India’s transition to the Income Tax Act, 2025 is not a clean switch in which the Income-tax Act, 1961 simply disappears from professional practice on 1 April 2026. For tax advisers, finance teams and businesses, the transition creates a period where two legal frameworks can operate side by side depending on the period of income and the proceeding involved.

The core issue: one calendar, two tax frameworks

The Income Tax Department’s transition FAQs clarify that income earned during FY 2025-26 remains governed by the Income-tax Act, 1961 for Assessment Year 2026-27, even though the return may be filed after 1 April 2026. By contrast, income earned from 1 April 2026 falls within Tax Year 2026-27 under the Income Tax Act, 2025. The result is a practical overlap: an assessee may be filing an AY 2026-27 return under the old Act while simultaneously maintaining records, deducting tax and paying advance tax under the new Act for Tax Year 2026-27.

Why AY 2026-27 still belongs to the 1961 Act

The Department has expressly stated that the return for income earned during FY 2025-26 is to be filed for AY 2026-27 under the Income-tax Act, 1961. This extends beyond the original return. Revised returns, belated returns, updated returns, defective-return responses and scrutiny proceedings relating to AY 2026-27 continue under the old Act. Section 536(2)(c) of the Income Tax Act, 2025 preserves proceedings relating to tax years beginning before 1 April 2026 under the earlier framework.

The compliance consequences professionals should not miss

First, the applicable return form must be chosen by reference to the relevant assessment year, not merely the date on which filing occurs. For AY 2026-27, taxpayers continue to use the forms notified under the 1961 Act. Second, any scrutiny notice for AY 2026-27 remains governed by the old assessment provisions even if issued after the new Act has commenced. Third, an updated return for AY 2026-27 may continue to be filed under section 139(8A) of the old Act subject to the applicable statutory conditions and time limits. Fourth, losses determined for AY 2026-27 can continue into the new regime, subject to the conditions governing carry-forward and set-off.

A records problem disguised as a tax problem

The transition increases the importance of year-tagged working papers. Tax teams should clearly distinguish FY 2025-26 / AY 2026-27 files from Tax Year 2026-27 files. Tax computation templates, return checklists, TDS reconciliations, advance-tax workings and litigation trackers should identify the governing statute on the face of the document. This is particularly important where the same taxpayer has an assessment under the 1961 Act while current-year transactions are governed by the 2025 Act.

Practical control points for businesses and advisers

A sensible transition control framework should include: separate compliance calendars for AY 2026-27 and Tax Year 2026-27; explicit statute references in tax memos and notices; review of ERP and tax-software mapping for the new tax-year framework; preservation of old-Act assessment documentation; reconciliation of brought-forward losses and credits; and partner-level review of cases where an old-Act proceeding interacts with current-year positions under the new law.

Professional takeaway

The biggest transition risk is not that professionals are unaware of the new Act. It is that they may apply the new Act to a matter that legally remains under the old one, or continue old-Act assumptions into a tax year governed by the new framework. For AY 2026-27, the period of income remains the controlling anchor. That distinction should drive return filing, assessment strategy, litigation positions and internal documentation.

Source note: This article is based on the Income Tax Department’s official FAQs on return filing and transition to the Income Tax Act, 2025, including its guidance on AY 2026-27, Tax Year 2026-27, revised/belated/updated returns, scrutiny proceedings and carry-forward of losses.

Disclaimer: This article is for general professional information only and does not constitute legal or tax advice. The applicable law, notifications, forms and facts of each case should be reviewed before taking a position or filing a return.