Short answer: two Acts are live at the same time. A notice about AY 2026-27 or earlier correctly cites 1961 Act sections — 143(1), 143(2), 148. A notice about tax year 2026-27 onwards cites the 2025 Act — 270(1), 270(8), 280. An old number on an old year is not a defect.
Why you are seeing two systems at once
The Income-tax Act, 2025 came into force on 1 April 2026. It did not sweep away everything before it. Section 536 of the 2025 Act — a savings provision running to 22 sub-clauses, reinforced by Section 6 of the General Clauses Act — preserves rights, liabilities, approvals, registrations and pending proceedings arising before that date, and lets them run to completion under the 1961 Act.
The practical consequence is a dual track that will persist for years:
| The year in question | Governing Act | Notice cites |
|---|---|---|
| AY 2026-27 (FY 2025-26) and earlier | Income-tax Act, 1961 | 143(1), 143(2), 148, 154 |
| Tax year 2026-27 onwards | Income-tax Act, 2025 | 270(1), 270(8), 280, 287 |
So the first question on receiving any notice is not "what does this section say" but "which year is this about". That determines everything else.
The notice-by-notice mapping
| Notice / order | 1961 Act | 2025 Act |
|---|---|---|
| Inquiry before assessment | s.142(1) | s.268 |
| Valuation reference / special audit | s.142A | s.269 |
| Intimation (summary processing) | s.143(1) | s.270(1)–(7) |
| Time limit for the intimation | s.143(1) proviso | s.270(4) — 9 months |
| Scrutiny notice | s.143(2) | s.270(8) |
| Time limit to serve it | s.143(2) proviso | s.270(9) — 3 months |
| Assessment order | s.143(3) | s.270(10) |
| Best judgment assessment | s.144 | s.271 |
| Faceless assessment | s.144B | s.273 |
| Dispute Resolution Panel | s.144C | s.275 |
| Reassessment — the core | s.147 | s.279 |
| Reassessment notice | s.148 | s.280 |
| Pre-notice inquiry procedure | s.148A | s.281 |
| Limitation for reassessment | s.149 | s.282 |
| Sanction for issuing notice | s.151 | s.284 |
| Rectification | s.154 | s.287 |
| Notice of demand | s.156 | s.289 |
| Under-reporting penalty | s.270A | s.439 |
| Penalty immunity application | s.270AA | s.440 |
| Appeal to Commissioner (Appeals) | s.246A / s.249 | s.357 / s.358 |
| Appeal to Tribunal | s.253 | s.362 |
| Appeal to High Court | s.260A | s.365 |
Two structural points behind the table:
Assessment is now one section, not several. The old 143(1), 143(2) and 143(3) were separate provisions. Under the 2025 Act all three live inside Section 270:
- 270(1)–(7) — processing and the intimation, with the nine-month outer limit at 270(4)
- 270(8) — the scrutiny notice, requiring you to attend or produce evidence
- 270(9) — no notice under 270(8) after three months from the end of the financial year in which the return is furnished
- 270(10) — the assessment order itself
When a new-Act notice arrives the sub-section tells you what kind of proceeding it is. Reading only "Section 270" tells you almost nothing — and 270(9) is where a late scrutiny notice is challenged.
Demand has moved to 289 — and 156 now means something else entirely. Section 156 of the 1961 Act was the notice of demand. Section 156 of the 2025 Act is the rebate for resident individuals. Two completely unrelated provisions sharing a number across the two Acts is exactly the kind of collision that produces a confident, wrong answer.
⚠️ A fresh 1961-Act notice can still arrive today
This is the point that catches people, including some advisers. The repeal did not extinguish old years.
The department can still issue a new notice under the 1961 Act for a pre-2026 year, after 1 April 2026, subject to the 1961 Act's own limitation periods. Section 536 preserves the power, not merely the paperwork already in motion.
So "the 1961 Act has been repealed, this notice is bad" is not an argument. The argument that does work is limitation — and limitation differs between the two Acts:
Under the 2025 Act the limits are in Section 282, and they differ depending on which notice you are holding:
| Notice | Ordinary limit | Extended limit |
|---|---|---|
| Show-cause under s.281 (ex-148A) | 4 years from end of the tax year | 6 years, where escaped income is ₹50 lakh or more |
| Reassessment notice under s.280 (ex-148) | 4 years and 3 months | 6 years and 3 months, on the same ₹50 lakh test |
Two further points from Section 282 worth having:
- The extended window for a s.280 notice requires the Assessing Officer to have books of account, documents or evidence showing escaped income of ₹50 lakh or more — not merely information. For the s.281 show-cause the test is framed as "information with the Assessing Officer". The evidential bar is not the same.
- Section 282(3): no notice under either section may issue within one year from the end of any tax year. There is a floor as well as a ceiling.
For old years the 1961 Act governs, and its limits were themselves recast with effect from 1 September 2024: 3 years 3 months ordinarily, extending to 5 years 3 months where the officer holds material showing escaped income of ₹50 lakh or more. The 10-year outer limit that a great deal of commentary still quotes belonged to the 2021 scheme and does not apply to notices under the recast provisions — see Section 148 reassessment notices: time limits and defences, which works through which version governs a given notice.
Checking a 1961-Act notice against 2025-Act time limits, or the reverse, produces the wrong answer in both directions. Our note on Section 148 reassessment notices works through the old-Act limitation position, which is the one that governs most notices arriving now.
The portal runs both years side by side
During FY 2026-27 the e-filing portal carries AY 2026-27 (FY 2025-26 income, 1961 Act) and tax year 2026-27 (2025 Act) at the same time. When paying tax you must select the right one.
A challan tagged to the wrong year does not fail — it sits against the wrong demand, leaves the intended demand outstanding, and generates interest and recovery follow-up until someone unpicks it. It is avoidable and tedious to fix.
What to check on any notice, in order
- Which year is it about? That fixes the Act.
- Is the section right for that year? An old number on an old year is correct. A new number on an old year is worth questioning.
- Is it within limitation under that Act's rules?
- Does it carry a DIN, and was it validly served?
- What is the deadline to respond, and the appeal window if it is an order?
Steps 3 to 5 are where replies are won or lost, and they are independent of the renumbering. For the substance of specific notices, see Section 143(1) intimation, Section 143(2) scrutiny and Section 142(1) inquiry.
For sections beyond the notice provisions, the full old-to-new mapping is the quick reference, and pending assessments and appeals after the repeal covers what happens to matters already in progress.
This is a working reference, not the statute. For anything you are filing or relying on, confirm the section text against the Act or the department's official 1961-vs-2025 comparison utility.