Start with the rule everyone gets wrong. The Income-tax Act, 2025 is in force from 1 April 2026 — but the return you file during 2026 is not under it. That return covers income of FY 2025-26 (AY 2026-27) and remains fully governed by the 1961 Act: old sections, old forms, old labels. Your first return under the new Act covers tax year 2026-27 and gets filed in 2027. Here is the whole transition, year by year.

The transition rule, plainly

The new Act applies to income earned from 1 April 2026 onwards — that is, from tax year 2026-27. Returns always follow the year they report. So:

Income earned inReturn filed inGoverning ActLabel
FY 2025-26 (Apr 2025 – Mar 2026)20261961 ActAY 2026-27
Tax year 2026-27 (Apr 2026 – Mar 2027)20272025 ActTax year 2026-27

If you remember nothing else: this year's filing season is business as usual under the old Act. The new-Act filing experience arrives next year. The background to the change — what the new Act keeps, drops and renumbers — is in our pillar guide to the Income-tax Act 2025 vs the 1961 Act.

The logic is simple once stated: a law can only fairly govern income earned while it was in force. FY 2025-26 income was earned entirely under the 1961 Act, so its return, its assessment and any later notice about it stay under the 1961 Act — forever. The 2025 Act picks up the first rupee earned on or after 1 April 2026 and everything that follows from it.

The AY 2026-27 calendar: where it stands

The AY 2026-27 calendar runs on the familiar 1961-Act framework (section 139(1)); as of 5 September 2026 the CBDT had not extended any of these dates:

  • 31 July 2026 — individuals and other non-audit cases (now past; a belated return can still be filed, with interest and late fee).
  • 31 October 2026 — taxpayers whose accounts require audit (in 2025 the CBDT extended the equivalent dates by circular; check the CBDT circulars list before relying on the statutory date).
  • 30 November 2026 — taxpayers with transfer-pricing reporting.
  • 31 December 2026 — last date for belated or revised returns.

Use the forms you know: ITR-1 to ITR-7, and for audit cases Forms 3CA/3CB/3CD. They are 1961-Act forms, and for this filing season they are the correct ones.

Deductions for this return are claimed under the old section numbers too — 80C, 80D, 87A and the rest — because they were the law during FY 2025-26. Do not let a new-Act article (including ours) tempt you into citing Section 123 on an AY 2026-27 return. The numbers must match the Act that governs the year.

The short version

File your FY 2025-26 return in 2026 exactly as you did last year — same Act, same forms, 31 July or 31 October deadline. The new Act first shows up in the return you file in 2027, for income you are earning right now.

Meanwhile, the paperwork around you has already changed

Here is the part that confuses people. The new Act took over deduction-side compliance on 1 April 2026, even though return filing has not switched yet. From April 2026:

  • Salary TDS is deducted under Section 392 (old 192); non-salary TDS under the table-based Section 393.
  • Your salary TDS certificate for tax year 2026-27 will be Form 130, not Form 16.
  • Your annual tax statement becomes Form 168, replacing Form 26AS.
  • Property, rent and contractor TDS challans use the consolidated Form 141, replacing 26QB–26QE.
  • Lower-TDS applications use Form 128 (old Form 13); foreign-remittance certificates use Forms 145/146 (old 15CA/15CB).

So during 2026 you may hold a Form 130 from your employer while filing an old-Act return that still references Form 16 data for last year. Both are correct — they belong to different years. The complete cross-reference is in our old vs new section and form mapping.

What your first new-Act return will look like (2027)

The label changes

You will file "for tax year 2026-27", not "for AY 2027-28". One label, matching the year you earned the income. The logic is unpacked in our explainer on the new "tax year".

The section references change

Deductions you claim will cite new numbers: 80C-type investments under Section 123, health insurance under Section 126, the rebate under Section 156. The return-filing obligation itself sits in Section 263 (old 139). Same entitlements, new addresses.

The numbers on your tax computation do not change

The new Act did not touch rates. The new-regime slabs (nil to ₹4 lakh, rising to 30% above ₹24 lakh), the rebate of up to ₹60,000 making income up to ₹12 lakh tax-free, the ₹75,000 standard deduction for salaried taxpayers, the ₹1.5 lakh investment-deduction cap — all carry over as they stood. The default new regime continues as Section 202, and the old regime remains an opt-in.

The data behind the return changes shape

Expect your pre-fill and reconciliation documents for tax year 2026-27 to carry the new names: TDS credits flowing from Form 130 (salary) and the consolidated Form 141 (property, rent, contractor payments), all summarised in Form 168 instead of Form 26AS. The reconciliation habit itself is unchanged — before filing, match what the statement shows against what was actually deducted from you. Mismatches remain the single most common cause of refund delays, under either Act.

Who will feel the change most

A salaried person with one employer and some bank interest will barely notice — new labels on familiar documents. Business owners will notice more: presumptive-scheme elections now cite Section 58 (which absorbed 44AD, 44ADA and 44AE), books-of-account obligations cite Section 62, and audit applicability cites Section 63. Deductors feel it most of all, since every TDS section and statement they touch was renumbered. NRIs sit in between — unchanged residency and rates, renumbered certificates and forms.

The ITR form names

For the AY 2026-27 season the familiar ITR-1 to ITR-7 continue (with ITR-U for updated returns). Return forms for the first new-Act filing in 2027 had not been notified as of 5 September 2026; the Income-tax Rules, 2026 notified on 20 March 2026 renumber the other forms — for instance the tax-audit report becomes a single Form 26 in place of Forms 3CA, 3CB and 3CD.

Missed or wrong returns: the 48-month window

The updated-return facility carries into the new Act: the 48-month window (extended by the Finance Act 2025) sits in section 263(6), and the additional tax on an updated return in section 267 (old 140B). If a year was missed or understated, it can usually still be set right — with additional tax that grows the longer you wait. It is a correction mechanism, not a substitute for filing on time.

This matters during the transition because old-year corrections do not migrate to the new Act. An updated return for, say, FY 2024-25 remains an old-Act filing with old-Act references, even if you submit it in 2028. Which Act applies is fixed by the year of income, permanently — not by the date you happen to press submit.

The transition year rewards taxpayers who keep one simple habit: write the year on everything. Which year the money was earned decides everything else.

A short transition checklist

  • The FY 2025-26 return is an old-Act return: the 31 July 2026 date for non-audit cases has passed (belated returns remain possible until 31 December 2026); audit cases run to 31 October 2026 unless extended.
  • Reconcile last year's TDS against Form 26AS one final time — next year the statement becomes Form 168.
  • If you run payroll or deduct TDS, confirm your 2026-27 deductions cite Sections 392/393 and the new statement forms.
  • Preserve old-Act records: pending refunds, carried-forward losses and open assessments for earlier years stay under the 1961 Act.
  • Expect your 2027 filing to carry new labels and section numbers — but substantially the same tax result.

For businesses, deductors and individuals with open matters under both Acts, a one-time transition review is worth the hour it takes. Our taxation practice handles return filing and new-Act transition planning across both regimes.

SL
Reviewed by CA. Sunil Kumar Lahoti Partner, S K Lahoti Associates, Chartered Accountants.

Frequently asked questions

No. The return filed during 2026 covers income of FY 2025-26 (AY 2026-27) and is governed entirely by the 1961 Act — old section numbers and the familiar ITR-1 to ITR-7 forms. The 2025 Act governs income earned from 1 April 2026 onwards.

In 2027, for tax year 2026-27 (income earned 1 April 2026 to 31 March 2027). That will be the first filing labelled by tax year rather than assessment year.

Under the 1961 Act framework: 31 July 2026 for non-audit individuals (now past; belated returns remain possible), 31 October 2026 for audit cases, 30 November 2026 for transfer-pricing cases, and 31 December 2026 for belated or revised returns — unless the CBDT extends a date by circular.

Yes, and that is correct. TDS deducted from 1 April 2026 falls under the new Act (Sections 392/393, new forms like 130 and 141), while the return you file in 2026 is an old-Act return for AY 2026-27. The two systems deliberately overlap during the transition year.

Not because of the new Act. Slabs, the ₹60,000 rebate up to ₹12 lakh, and deduction limits carry over unchanged. Any rate changes would come from a Finance Act, exactly as they always have.

The updated-return window is 48 months, as extended by the Finance Act 2025 and carried into the new Act in section 263(6); the additional tax is in section 267. Additional tax applies, increasing the later you file within the window.

Want this filing season and the next one planned together? Write to the firm — a partner will map your transition.

References

Position stated as on 5 September 2026 · sources checked 5 September 2026.

  1. Income-tax Act, 2025 (30 of 2025), in force from 1 April 2026 — section 1(3) (commencement), section 263 (return of income and the table of due dates), section 263(6) (updated return within forty-eight months) and section 267 (additional tax on an updated return). Act text, CBDT
  2. Income-tax Rules, 2026 — Notification No. 22/2026 [F. No. 370142/41/2025-TPL] / G.S.R. 198(E), 20 March 2026 (CBDT) — Form 26 replacing Forms 3CA, 3CB and 3CD; Form 141; Form 168. CBDT table of forms under the 2026 Rules against the 1962 Rules
  3. CBDT, Income Tax Returns for 2026 (assessment year 2026-27): Forms ITR-1 (Sahaj) to ITR-7, ITR-V, ITR-U (updated return within forty-eight months) and ITR-A; no return forms had been notified under the 2026 Rules for the tax year 2026-27 as on 5 September 2026. Income Tax Returns, CBDT
  4. CBDT circulars issued in 2026 (Nos. 1/2026 to 6/2026, the latest dated 2 July 2026): none extends the assessment year 2026-27 return due dates in section 139(1) of the Income-tax Act, 1961; the 2025 extensions were Circulars 6/2025, 12/2025, 14/2025 and 15/2025. Circulars, CBDT