Income Tax

Tax Year vs Assessment Year Under the New Income-tax Act: Simple Guide

Finin2min Tax Desk·June 2026·7 min readTAX YEAR

A lot of tax mistakes start with date confusion. Under the Income-tax Act, 2025, “tax year” becomes the key reference point. That makes it even more important not to mix the income period with the return-processing year or old assessment-year language.

For broader context, see the Income Tax and Salary Hub.

The basic date logic

The Income-tax Act, 2025 is effective from 1 April 2026. The Act’s official section-wise page includes a dedicated Section 3 for definition of “tax year”. In simple terms, income from 1 April 2026 to 31 March 2027 is part of Tax Year 2026-27, not the return year by itself.

Use the Income Tax Calculator – Tax Year 2026-27 & FY 2025-26 — New vs Old Regime to apply these points to your figures or facts.

Why this matters in articles and calculators

Wrong phrasing	Better phrasing
“FY 2026-27 return due on 31 July 2026”	Tax Year 2026-27 ends on 31 March 2027; return due date must be checked for the later filing cycle.
“AY 2026-27 income under new Act”	Be careful: income year and filing/assessment labels may not be identical.
“Old Act always applies to AY 2026-27”	Check tax year and transition/saving provisions.

For the connected rule, example or next step, see Form 16 Reconciliation Under New Income-tax Act 2025.

Practical examples

Salary earned in May 2026: governed by the 2025 Act framework unless a specific saving applies.
Return for income earned April 2026–March 2027: check official tax calendar and e-filing forms for the relevant filing due date.
Appeal or correction for an earlier year: may continue under 1961 Act as per transition rules.

Finin2min publishing rule

Always write dates in three layers: income period, tax year, and filing/due-date period. This avoids the common mistake of putting a 2026 due date against income that has not even fully accrued until March 2027.

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Make compliance less reactiveKeep a tax-year evidence file with official due dates, section references, proofs and regime comparison before filing season.

Open Calculators →

Official sources used

This article is built only from official Income Tax Department and e-filing portal sources. Always verify the live Act, Rules, forms and tax calendar before filing.

For the connected rule, example or next step, see New Income-tax Act 2025 Transition Calendar for Employers.

FAQs

What is the key change in terminology?▾

The 2025 Act uses “tax year” as a key concept, with the official Act page listing Section 3 as the definition of tax year.

Is Tax Year 2026-27 the same as the filing due date in 2026?▾

No. Tax Year 2026-27 covers income for the year ending 31 March 2027; filing due dates must be checked separately.

How should Finin2min avoid date errors?▾

State the exact income period and separately state the return filing/due-date period using the official tax calendar.

Source and review trail

Use the current official instrument, portal or regulator publication before acting. This panel separates the category authority from page-specific references.

Primary category: Income Tax
Official starting point: www.incometax.gov.in

Page source links

For the connected rule, example or next step, see Income Tax Slabs for FY 2025-26 (AY 2026-27): New Regime vs Old Regime.