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Income Tax Act 2025 vs 1961: Old to New Section Mapping

Last reviewed: July 2026 · Sourced from official government portals

01

The One-paragraph Answer

The Income-tax Act 2025 replaced the Income-tax Act 1961 on 1 April 2026, renumbering essentially every section while keeping the substantive rules largely intact: return filing moved from Section 139 to Section 263, the 143(1) intimation became 270(1), reopening moved from 147/148/148A to 279/280/281, and advance tax from 207-211 to 403-408. Which Act applies depends on the year: AY 2026-27 (FY 2025-26) and everything earlier stays on the 1961 Act, while FY 2026-27 onwards runs on the 2025 Act.

This page is a lookup table. If a notice, order or article quotes a section you do not recognise, find its old or new counterpart below, then follow the link to the detailed guide for that notice type.

02

Which Act Governs Your Case: The Savings Clause

Section 536(2)(c) of the new Act is the transition rule that decides everything. Proceedings, notices and assessments relating to periods before 1 April 2026 continue under the 1961 Act as if it had not been repealed. In practice:

  • •ITR for AY 2026-27 (income of FY 2025-26), filed during 2026: old Act. Belated and revised returns for this year cite Section 139(4)/(5), late fee cites 234F.
  • •A scrutiny or reopening notice received in 2026 for AY 2023-24: old Act. It will cite 143(2) or 148, and replies are drafted under the 1961 framework.
  • •TDS on payments made from 1 April 2026: new Act (Sections 392/393/394).
  • •ITR for FY 2026-27, filed in 2027: new Act. Filing provision is Section 263.
  • •An intimation issued in 2027 for the FY 2026-27 return: new Act, Section 270(1).

The most common confusion in 2026-27 is receiving old-Act notices and new-Act challans in the same month. Both are correct; they belong to different years.

03

Return Filing: Section 139 Becomes Section 263

The whole return-filing machinery of Section 139 now lives in Section 263 of the 2025 Act, with the familiar sub-provisions renumbered as sub-sections.

What it does1961 Act2025 Act
Filing the annual return139(1)263(1)
Belated return139(4)263(4)
Revised return139(5)263(5)
Updated return (ITR-U)139(8A)263(6)
Defective return139(9)corresponding provision in 263

Deadlines carried forward: belated and revised returns remain due by 31 December following the assessment year, and the ITR-U window remains 48 months.

04

Assessment And Scrutiny: The 14x Series Becomes The 26x-27x Series

Every assessment-stage notice was renumbered. If a notice cites one of these new sections, the process and your response options are the same as under the old counterpart.

Notice / proceeding1961 Act2025 Act
Inquiry before assessment (asking for documents)142(1)268(1)
Intimation after CPC processing143(1)270(1)
Scrutiny selection notice143(2)270(2)
Best judgment assessment144271
05

Reopening Of Past Years: 147/148/148a Become 279/280/281

The reassessment framework that was rewritten in 2021 (income escaping assessment, notice, and the mandatory prior show-cause) moved as a block.

What it does1961 Act2025 Act
Income escaping assessment (the power)147279
Reassessment notice148280
Prior show-cause before reopening148A281

Reopening notices issued in 2026 and 2027 for AY 2026-27 and earlier will still cite 148/148A because of the savings clause. Expect 280/281 notices only once FY 2026-27 assessments age into reopening range.

06

Demand, Advance Tax And Interest

The payment-side provisions renumbered as follows.

What it does1961 Act2025 Act
Notice of demand156289
Advance tax liability and schedule207-211403-408
Interest for advance tax shortfall234B424
Interest for deferred instalments234C425
Late filing fee (Rs 5,000 / Rs 1,000)234Fcorresponding fee provision in the 2025 Act

Rates are unchanged: 1% per month under 424/425, the 15/45/75/100 advance tax schedule, and the Rs 10,000 advance tax threshold all carry forward.

07

Tax Audit And Tds

Two mappings matter for businesses more than any other.

What it does1961 Act2025 Act
Tax audit requirement (turnover limits)44AB63
Penalty for audit failure271B446
TDS on salary192392
TDS on non-salary payments (whole 194-series)194A to 194Q393 + Schedule I
TCS206C394

The TDS consolidation is the biggest structural change in the new Act; the dedicated FY 2026-27 TDS guide covers challan codes and the new return forms.

08

How To Read A Notice That Arrives After April 2026

A three-step check tells you which framework you are in before you draft a single line of reply.

  • •Check the assessment year or tax period on the notice. AY 2026-27 or earlier: 1961 Act. FY 2026-27 onwards: 2025 Act.
  • •Check the section quoted against the tables above. A 270(1) intimation is answered exactly like a 143(1) intimation; a 280 notice like a 148 notice.
  • •Check the response deadline on the notice itself. Renumbering did not relax a single deadline; the 30-day windows on intimations and demands operate as before.

Do not cite new-Act sections when replying to an old-Act notice or vice versa. Mismatched citations do not invalidate a reply, but they signal confusion and invite avoidable queries.

09

What Did Not Change In Substance

The 2025 Act was consciously drafted as a simplification, not a policy rewrite. For most taxpayers the following are untouched.

  • •Tax slabs and both regimes as they stood after the Finance Act 2025.
  • •The concept of the 'tax year' replaces 'previous year/assessment year' terminology in the new Act, but the underlying periods align with financial years.
  • •Appeal hierarchy: faceless assessment, CIT(A), ITAT and beyond continue.
  • •Advance tax schedule, interest rates, late fee amounts, audit turnover thresholds.
  • •Refund, rectification and grievance processes on the e-filing portal, which now displays both old and new section references during the transition years.
FAQ

Frequently Asked Questions

Yes. Section 270(1) of the Income-tax Act 2025 is the CPC processing intimation, the direct successor of 143(1). It means your return for a tax year governed by the new Act (FY 2026-27 onwards) was processed, with a demand, a refund, or no change. The response options are the same: pay within 30 days, seek rectification, or respond to the demand on the portal.

The 1961 Act. AY 2026-27 (income of FY 2025-26) is the last year on the old Act, under the savings clause in Section 536(2)(c) of the new Act. Your return cites Section 139, late fees cite 234F, and any belated or revised filing before 31 December 2026 is under 139(4)/139(5).

Yes. For assessment years before the new Act (AY 2026-27 and earlier), reopening continues under Sections 147/148/148A of the 1961 Act because pending and future proceedings for those years are saved by Section 536(2)(c). A 148 notice received in 2026 or 2027 for an old year is valid and is answered under the old framework, including the 148A show-cause safeguards.

The deduction provisions were regrouped into a new numbering scheme rather than mapped one-to-one, and most 80C-style deductions matter only under the old regime anyway. For the deduction chapter, work from the official mapping utility on incometax.gov.in rather than assuming a single-section counterpart, since several old sections were merged or split.

No. The updated return moved from Section 139(8A) to Section 263(6) with the 48-month window and the 25%/50%/60%/70% additional tax slabs intact. The additional tax computation provision (old 140B) has its counterpart in the new Act as well. The mechanics are covered in the dedicated ITR-U guide.

For FY 2026-27, the scrutiny notice issues under Section 270(2) of the new Act, and the assessment order will be under the new Act's assessment provision, so old-Act citations are technically incorrect for that year. It will not by itself invalidate the reply, but ask for the citations to be corrected; assessment orders and appeals for new-Act years should consistently use new-Act sections.

For filing behaviour, no: the portal guides you to the right forms. Where action is needed is in systems and documents that hard-code section numbers: TDS software and challan mappings, rent agreements and contracts that quote TDS sections, salary structures referencing old-Act provisions, and internal compliance calendars. Those should be updated to dual references during 2026-27.

How we reviewed this page

The penalty amounts, deadlines, and regulatory requirements on this page are sourced directly from official government portals. We do not use secondary sources. When regulations change, we update the page.

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