Income Tax Act Explained: Structure, Key Provisions and the 2025 Update

What is the Income Tax Act?

The Income Tax Act, 1961, is the principal legislation governing direct taxation of income in India, laying down who is liable to pay income tax, how taxable income is computed across different categories, what deductions and exemptions are available, and the procedural framework for filing returns, assessment, appeals, and penalties, administered by the Income Tax Department under the Central Board of Direct Taxes.

Since its enactment, the Act has been amended almost every year through the Finance Act, which accompanies the Union Budget, meaning the core 1961 framework has absorbed six decades of incremental changes, insertions, and deletions, a pattern that eventually made the law genuinely difficult to navigate even for tax professionals.

How the Income Tax Act 1961 Is Structured

The Act is organized into chapters and sections, broadly covering definitions, the basis of charge, heads of income, income exempt from tax, deductions, aggregation and set-off of losses, procedures for assessment and appeals, and provisions for specific categories of taxpayers like companies, trusts, and non-residents. Over the decades, insertions like Section 80C, Section 115BAC for the new tax regime, and numerous sub-clauses lettered 80CCD, 80CCH, and similar have been layered onto the original structure, which is part of why navigating the Act by section number alone has become genuinely challenging without professional guidance or updated reference material.

Key Heads of Income Under the Act

What are the heads of income under the Income Tax Act?

The Act classifies all taxable income under five heads: Income from Salary, Income from House Property, Profits and Gains of Business or Profession, Capital Gains, and Income from Other Sources, with each head carrying its own specific computation rules, allowable deductions, and exemptions.

Important Sections Every Business Owner Should Know

• Section 139 covers the requirement and due dates for filing income tax returns, including provisions for belated and revised returns.
• Section 44AB governs mandatory tax audit requirements for businesses and professionals crossing specified turnover or gross receipts thresholds.
• Section 80C and related sub-sections like 80CCD cover common deductions available under the old tax regime, including investments, insurance premiums, and retirement contributions.
• Section 115BAC governs the new tax regime, now the default option for most taxpayers unless they actively opt for the old regime.
• Section 194 series covers tax deductible at source provisions, specifying who must deduct tax and at what rate across various payment types like salary, rent, professional fees, and contractor payments.
• Section 10 lists categories of income specifically exempt from tax, relevant to structuring compensation, allowances, and certain categories of business income.

The New Income Tax Act 2025: What’s Changing

What is the Income Tax Act, 2025?

The Income Tax Act, 2025, is a comprehensively rewritten replacement for the 1961 Act, passed to simplify the language, structure, and section numbering of India’s income tax law without fundamentally altering tax rates or policy, coming into effect from 1 April 2026, aimed at making the law more accessible and easier to navigate after decades of incremental amendment had made the original Act unwieldy.

The rewrite reorganizes provisions into a more logical sequence, removes redundant and obsolete clauses accumulated over sixty-plus years, and renumbers sections in a cleaner structure, while generally preserving the substantive tax treatment taxpayers are already familiar with under the 1961 Act’s core provisions, including the existing dual old-regime and new-regime structure.

Why the Law Was Rewritten Rather Than Just Amended

A law amended continuously for over sixty years inevitably accumulates structural problems that simple further amendment cannot fix: provisions get renumbered awkwardly with sub-clauses like 80CCD and 115BAC stacked onto an original numbering scheme never designed for this much expansion, cross-references become harder to follow, and obsolete provisions remain on the books long after they stop being relevant. Rewriting the Act from scratch, while preserving the underlying policy and tax treatment, was the government’s chosen path to address this structural debt directly rather than continuing to patch an increasingly strained original framework.

What This Means for Businesses and Individuals

For a business already familiar with specific section numbers under the 1961 Act, the transition to the Income Tax Act 2025 means relearning the updated numbering and structure, even though the underlying tax treatment for most common provisions is expected to remain substantively similar. Businesses should update their internal compliance references, accounting software configurations, and any contractual language citing specific old-Act section numbers and should work with their tax advisor to map previously familiar provisions to their new location under the 2025 Act as the transition takes effect.

Key Takeaways

• The Income Tax Act, 1961, has governed India’s direct taxation for over six decades, organized around five heads of income and layered with amendments through annual Finance Acts.
• Key sections every business owner should know include Section 139 for return filing, Section 44AB for tax audit, Section 115BAC for the new tax regime, and the Section 194 series for TDS.
• The new Income Tax Act, 2025, takes effect from 1 April 2026, comprehensively restructuring and simplifying the law’s language and section numbering without fundamentally changing tax policy or rates.
• The rewrite addresses structural complexity built up over sixty years of incremental amendment, rather than representing a change in substantive tax treatment.
• Businesses should update internal references and work with their tax advisor to map familiar 1961 Act provisions to their new location under the 2025 Act.

FAQs

What is the Income Tax Act in India?

The Income Tax Act, 1961, is India’s principal legislation governing the levy, computation, and collection of income tax, covering who must pay tax, how income is classified and computed, and the procedural framework for filing and assessment.

What are the five heads of income under the Income Tax Act?

Salary, House Property, Profits and Gains of Business or Profession, Capital Gains, and Income from Other Sources.

When does the new Income Tax Act 2025 take effect?

The Income Tax Act, 2025, takes effect from 1 April 2026, replacing the Income Tax Act, 1961.

Does the new Income Tax Act 2025 change tax rates?

No, the 2025 Act is primarily a structural and language simplification of the existing law, generally preserving the substantive tax treatment and rates taxpayers are already familiar with.

What is Section 115BAC of the Income Tax Act?

Section 115BAC governs the new tax regime, which has been the default tax regime for most taxpayers since its introduction, unless they actively opt for the old regime instead.

Why was the Income Tax Act rewritten instead of just amended again?

Over sixty years of continuous amendment had made the original 1961 Act structurally complex and difficult to navigate, so the government chose a comprehensive rewrite to simplify language and numbering while preserving underlying tax policy.

Conclusion

Navigating which provisions of the Income Tax Act apply to your business, and preparing for the transition to the new Income Tax Act 2025, is easier with professional guidance. Book a free consultation with Growthora Advisory’s taxation team today.