Under the Income-tax Act, 1961, every taxpayer learned to juggle two overlapping years: the "previous year" (when you earned the income) and the "assessment year" (when you file and get assessed on it) — always one year apart, always a little confusing to explain to someone new to Indian taxes. The Income-tax Act, 2025 collapses both into a single term: tax year. Here's exactly how the mapping works.
The direct mapping
| Old Act (1961) terminology | New Act (2025) terminology |
|---|---|
| Previous Year 2025-26 (income earned Apr 2025 - Mar 2026) | Not applicable — governed by the old Act |
| Assessment Year 2026-27 (filing/assessment for the above) | Not applicable — governed by the old Act |
| Previous Year 2026-27 (income earned Apr 2026 - Mar 2027) | Tax Year 2026-27 |
| Assessment Year 2027-28 (filing/assessment for the above) | Same period — folded into Tax Year 2026-27, no separate label |
The critical point: income earned in the year running from April 2025 to March 2026 — what you're filing a return for right now, by 31 July 2026 — is still governed by the old Act's "previous year"/"assessment year" framework, since that income was entirely earned before the new Act took effect. "Tax year" as a term only starts applying to income earned from 1 April 2026 onward.
Why the change actually simplifies things
The old system required a small mental translation every time: "I earned this in the previous year, but I'm being assessed on it in the assessment year, which is the year after." The new system just says "Tax Year 2026-27" and means both the earning and the reporting period tied to that single label — one number to remember instead of two shifting by exactly one year from each other.
Edge cases worth knowing
NRIs and mid-year residency changes
The tax-year concept doesn't change how residential status itself is determined (day-count tests under Section 6 remain the operative rule) — it only changes the label applied to the 12-month period being assessed. An NRI whose residential status shifts partway through a tax year still has that entire tax year's income assessed under whichever status rules apply, exactly as under the old previous-year/assessment-year system.
Fiscal-year references in contracts and financial statements
Company financial statements, loan agreements, and other documents that reference "financial year" (FY) continue to use that term unchanged — FY and the new "tax year" for individual income tax purposes cover the same April-March window, so no separate reconciliation is needed for most purposes, but read any legal document's specific definitions rather than assuming.
Documents that still say "assessment year"
Expect banks, employers, and even government portals to reference "assessment year" for some time during the transition, especially for anything relating to income earned before April 2026. This isn't an error — it's the correct term for that older income.
For the complete picture of what else changed under the new Act — Form 16 becoming Form 130, TDS section renumbering, and the updated ITR deadlines — see our full Income-tax Act, 2025 guide.
Frequently Asked Questions
Is "Tax Year 2025-26" the same period as "AY 2026-27"?
No — this is the most common confusion. "Tax Year 2025-26" isn't used at all; income earned in that window is still called "Previous Year 2025-26" and assessed as "AY 2026-27" under the old Act, since that income predates the new Act. "Tax Year" terminology starts with the 2026-27 period (income earned from April 2026).
Do I need to change how I write dates on any documents I'm filing right now?
No — your current filing (covering income through March 2026) correctly uses "FY 2025-26 / AY 2026-27." Continue using that terminology for this filing season.
Does the government's own e-filing portal already use "tax year" language?
Portal terminology updates roll out on their own schedule; expect a transition period where both terms appear depending on which tax year's data you're viewing.
Why did the previous system need two separate years at all?
It reflected a two-step process: earn income in one year, then have it formally assessed the following year once returns are due and processed. The new Act keeps the same practical timeline but avoids naming it as two separate "years."
Does this change when my ITR is actually due?
No — filing deadlines are unaffected by this terminology change. The 31 July deadline for salaried individuals and the other category-specific deadlines remain governed by the applicable Finance Act provisions.
Will old tax documents referencing "AY" become invalid or need reissuing?
No — historical documents remain valid records of the period they describe. There's no requirement to reissue or relabel anything already filed.