The "Tax Year": How the New Act Ends Previous Year / Assessment Year Confusion

For six decades, every year of income in India carried two names. You earned in a "previous year" and were taxed in an "assessment year" — and choosing the wrong one on a challan or return was one of the most common taxpayer errors in the country. From 1 April 2026, the Income-tax Act, 2025 replaces both with a single label: the tax year. Here is what that means in practice.

The old system, briefly

Under the 1961 Act, the year you earned income was the previous year (PY) — the financial year from 1 April to 31 March. The year after it, in which that income was assessed and your return was filed, was the assessment year (AY).

So salary earned between April 2024 and March 2025 belonged to PY 2024-25 but was filed and assessed in AY 2025-26. Same money, two labels, always one year apart.

The confusion this caused was not trivial. Selecting AY 2024-25 instead of AY 2025-26 on a self-assessment challan meant the payment landed against the wrong year. Refunds got delayed. Demands appeared for years that were actually paid. CA offices spent every July explaining the difference from scratch.

The new system: one tax year

Section 3 of the Income-tax Act, 2025 defines the tax year: the 12-month financial year beginning 1 April. That is the whole system. You earn income in a tax year. You report it for that same tax year. The return is still filed after the year ends — that part of the calendar does not move — but the filing now carries the label of the year the income was earned, not the year after.

Worked examples: old labels vs new labels

Example 1 — a salaried employee

Priya earns salary from April 2026 to March 2027.

	Old (1961 Act) labels	New (2025 Act) labels
Income earned	PY 2026-27	Tax year 2026-27
Return filed (2027)	For AY 2027-28	For tax year 2026-27
TDS certificate	Form 16 for AY 2027-28	Form 130 for tax year 2026-27

Nothing about Priya's tax changes. The label on every document simply matches the year she earned the money.

Example 2 — the transition year (this is the one to get right)

Rohan is filing his return in July 2026 for income earned April 2025 to March 2026.

Income of	Governing Act	Label on the return
FY 2025-26 (filed in 2026)	1961 Act	AY 2026-27 — old labels still apply
FY 2026-27 (filed in 2027)	2025 Act	Tax year 2026-27 — first new-Act return

Note the trap: "2026-27" appears in both rows but means different things. AY 2026-27 refers to last year's income under the old Act. Tax year 2026-27 refers to this year's income under the new Act. During the transition, always check whether a document says "AY" or "tax year" before assuming which 12 months it covers. The full transition picture is in our pillar guide to the Income-tax Act 2025 vs the 1961 Act.

Example 3 — a new business

Under the 1961 Act, a business set up mid-year had its first "previous year" run from the date of setting up to 31 March. The 2025 Act keeps the same logic for the tax year: a first tax year can be shorter than 12 months, beginning with the date of setting up. The concept carried over; only the name changed.

Example 4 — an NRI checking residency

Meera, an NRI, counts her days in India to test the 182-day rule. Under the old Act she counted days in the previous year; under the new Act she counts days in the tax year. The same 1 April to 31 March window, the same thresholds. Residency outcomes do not change — see our companion guide to NRI taxation under the new Act.

Example 5 — paying tax during the year

Arjun pays advance tax on business income he is earning in 2026-27. Under the old system, the challan for income earned in FY 2026-27 had to be tagged to AY 2027-28 — a year that, to a normal person, sounds like the wrong one. That mismatch is precisely where wrong-year payments came from. Under the new Act, tax paid on tax year 2026-27 income is tagged to tax year 2026-27. The label on the challan finally matches the year the money relates to. The same logic applies to TDS: tax deducted from a payment made in a given tax year is credited against that tax year.

Why did the old system exist at all?

The two-label design was not an accident. The 1961 Act was built around the idea that income is first earned, then formally assessed by the department in the following year — so the law gave each step its own year. Over the decades, self-assessment, TDS and online processing made the formal assessment year largely invisible to taxpayers, but the vocabulary survived in every form and challan. The 2025 Act simply retired a label that no longer described how the system works. Earn, report, done — one year.

What does not change

• The filing calendar. Returns are still filed after the year ends. Relabelling does not move deadlines.
• The financial year for books. Accounts, GST and company-law filings continue to run April to March and to say "FY". For income-tax purposes, the statutory word is now "tax year" — the 12 months are identical.
• Old-year proceedings. Notices, assessments and appeals for periods up to FY 2025-26 continue under the 1961 Act and keep their AY labels. Expect both vocabularies to coexist for several years.

The two-label system caused more wrong-year challans than any other feature of the 1961 Act. Retiring it is the simplest, most useful thing the new Act does.

Why this matters beyond convenience

Labels drive systems. Challans, TDS statements, refunds and demand notices are all matched by year. A single label means fewer mismatches between what you paid and what the department recorded — and fewer hours spent getting wrong-year credits moved. For businesses with multi-year matters — carried-forward losses, reopened assessments, appeals — mapping old AY references onto new tax-year references accurately is part of transition housekeeping. Our taxation practice handles this mapping as part of new-Act compliance reviews.

Unsure which label — or which Act — applies to a year you are dealing with? Write to the firm and we will set it straight.