New Income Tax Act 2025: Complete Guide to India's Tax Law Overhaul Effective April 2026

India's income tax law is undergoing its most significant structural overhaul in over six decades. The Income Tax Act, 2025, which received Presidential assent in August 2025, comes into force on April 1, 2026. It replaces the Income Tax Act, 1961, which had accumulated decades of amendments, provisos, explanations, and judicial interpretations. The new Act does not fundamentally alter the tax base or rates but rewrites the law in plain language, consolidates scattered provisions, and eliminates internal inconsistencies that had generated years of litigation.

Why the 1961 Act Was Replaced

The 1961 Act had grown from its original 298 sections to over 800 sections by 2024, with thousands of sub-clauses, provisos, and explanations layered on top of the original framework. The language was archaic, cross-references were difficult to navigate, and the same concept was sometimes defined differently in different chapters. The Direct Tax Code project, which had been attempted multiple times since 2009, was ultimately abandoned. The 2025 Act takes a different approach: it restructures and simplifies existing law rather than changing the underlying tax policy.

What Changes Under the New Act

The most visible change is structural. Tax rates, slabs, and the basic exemption limit remain aligned with what was prescribed under the 1961 Act for FY 2025-26. The new Act introduces a cleaner chapter-based structure: income under each head is covered in a dedicated chapter with all relevant provisions, deductions, and computation rules in one place. Defined terms have been standardised across chapters. Redundant provisions that had become obsolete due to subsequent legislation have been removed. The new Act also introduces a table-based format for exemptions and deductions, replacing narrative provisos with structured schedules that are easier to read and apply.

What Stays the Same

The five heads of income remain: salaries, house property, profits and gains from business or profession, capital gains, and income from other sources. The fundamental concepts of residence and source, aggregation of income, set-off and carry-forward of losses, and the advance tax regime are preserved. All substantive judicial precedents under the 1961 Act remain relevant and applicable to the extent the underlying provision has been carried over, which the government has clarified through transition guidance. TDS and TCS mechanisms, return filing obligations, and assessment procedures are retained with structural improvements.

Transition Provisions and Pending Proceedings

Assessment proceedings for years prior to FY 2026-27 will continue under the 1961 Act. This means businesses and individuals with open scrutiny assessments, reassessments, appeals before the CIT(A), ITAT, or High Courts will continue to be governed by the old Act for those specific proceedings. The 2025 Act applies prospectively to income earned from April 1, 2026 onwards. The Finance Bill 2026 has clarified that references in agreements, contracts, or other documents to provisions of the 1961 Act will be read as references to corresponding provisions of the 2025 Act.

Practical Steps Before April 1

Businesses should map their existing tax positions, deferred tax computations, and compliance calendars against the new Act's chapter structure to confirm that relevant provisions have been correctly identified. Tax teams should update return preparation software, internal compliance checklists, and TDS obligation registers. Contracts referencing specific sections of the 1961 Act should be flagged for review. Individuals with complex income structures, including multiple employers, business income, or capital gains, should verify how their positions translate under the new Act's consolidated framework. The April 1 deadline is firm and the government has indicated no phase-in period for the new Act's application.