Section 3 of the Income-tax Act, 2025 — Definition of "Tax Year" (Meaning, Rules & Examples)

In plain language

What Section 3 says in plain English

Section 3 of the Income-tax Act, 2025 defines the single most important time-period in the whole Act — the "tax year". In simple words, the tax year is the twelve-month period of the financial year commencing on 1st April. So a normal tax year runs from 1 April to 31 March of the next calendar year (for example, 1 April 2026 to 31 March 2027).

This one word — "tax year" — replaces two older, confusing terms from the Income-tax Act, 1961: "previous year" (the year in which you earned the income) and "assessment year" (the next year in which the income was taxed). From 1 April 2026, both are gone. There is now just ONE year for both earning and assessing income.

Why this change was made

• To end the two-year confusion. Under the old law, income of 1961's "previous year" (say FY 2024-25) was taxed in the "assessment year" (AY 2025-26). Beginners constantly mixed up which year to write on returns and challans.
• One unified period. The tax year now covers both the earning of income and its assessment in the same 12 months. Income of Tax Year 2026-27 is dealt with as Tax Year 2026-27 — there is no separate "next" assessment year label.
• Global alignment. Most countries already use a single "tax year". India's new terminology matches international practice and makes the law easier to read.

Who this applies to

Section 3 applies to every taxpayer under the Act — salaried individuals, pensioners, freelancers, professionals, businesses, firms, LLPs, companies, trusts, HUFs and non-residents. Every provision of the Act that measures income, allows deductions, sets thresholds or fixes due dates is anchored to the "tax year" defined here.

The special rule for new businesses and new income sources

Section 3 contains a second, important limb. If a business or profession is newly set up, or a new source of income first comes into existence during a financial year, the tax year for that activity is not a full 12 months. Instead it is a shorter period that:

• begins on the date the business/profession is set up, or the date the new source of income comes into existence; and
• ends on 31 March of that same financial year.

This mirrors the treatment under the old Section 3 of the 1961 Act (which defined "previous year"), so the underlying principle is unchanged — only the name is new.

How Section 3 interacts with other provisions

• Section 2 (Definitions): "financial year" and other core terms are defined there; "tax year" builds on "financial year".
• Charge of tax: Income tax is charged on the total income of the tax year at the rates in the relevant Finance Act.
• Residential status & scope of income: Residency is tested for each tax year, deciding what income is taxable in India.
• Return filing & due dates: ITR due dates (e.g. 31 July / 31 October) are all counted from the end of the tax year.

Practical implications for you

• Fewer mistakes on forms. You now quote a single "Tax Year" (e.g. 2026-27) instead of separately tracking previous year and assessment year.
• Effective date matters. The tax-year system applies to income earned from 1 April 2026 onwards (Tax Year 2026-27). Income up to 31 March 2026 is still governed by the 1961 Act's previous-year/assessment-year framework.
• Books & accounting stay the same. The financial year 1 April–31 March is unchanged; only the tax terminology is simplified. Your ₹ figures, slabs and deductions are computed exactly as before.