The updated return is the most useful provision most practices under-use, and the reason is that the summaries of it are all slightly out of date.
The window is no longer twenty-four months. There are now four rates rather than two. There is a further ten per cent in a case that did not exist eighteen months ago. And for the year after next the whole thing becomes a different form under a different Act.
Everything below is the provisions themselves. Where the law does not settle something, this says so rather than filling the hole, because the holes are where the expensive mistakes are.
Forty-eight months, and a form title that still says twenty-four
Section 139(8A) lets a person furnish an updated return "at any time within forty-eight months from the end of the relevant assessment year", whether or not a return was furnished under 139(1), 139(4) or 139(5).
"Forty-eight" was substituted for "twenty-four" by Act No. 7 of 2025 with effect from 1 April 2025. Four years, not two.
The prescribed form is Form ITR-U, under rule 12AC(1) of the Income-tax Rules, 1962, for the assessment year commencing 1 April 2020 and subsequent years.
Worth knowing before somebody quotes it at you: the forms list at the end of the consolidated Rules still titles ITR-U "within twenty-four months". The Act governs and the title is stale. If a junior tells you the window closed, that heading is probably why.
Important
Rule 12AC(2) requires a digital signature where the accounts are audited under 44AB, and allows either a digital signature or an electronic verification code for everyone else. Working out the figures is not filing: the return is signed on the portal.
Three provisos, and what each one bars
The bars are the part worth checking first, because they are absolute and because two of the three turn on facts no document in your file contains.
The first proviso is about the return itself. An updated return may not be a return of a loss, except in the case the sixth proviso now covers. It may not have the effect of decreasing the total tax liability determined on the basis of the return already furnished. And it may not result in a refund, or increase the refund due, on that basis.
Those three are arithmetic. Given the earlier return's figures you can test all of them.
The second proviso is about search and survey. Where a search under 132 or a requisition under 132A has been initiated, or a survey conducted under 133A other than 133A(2A), or a notice issued that seized assets or seized books of another person belong or relate to the person, no updated return may be furnished for the assessment year relevant to the previous year in which that happened, or for any earlier assessment year. One event bars a run of years, not a single year.
The third proviso is about the year. Only one updated return per assessment year. None where a proceeding for assessment, reassessment, recomputation or revision is pending or completed for that year. None where the Assessing Officer holds information under the Smugglers and Foreign Exchange Manipulators Act, the Benami Act, the Prevention of Money-Laundering Act or the Black Money Act.
Pro tip
Ask the search and survey question before you work out a single figure. It is the only bar that can wipe out four years of options at once, and it is the one no file on your desk can answer.
What it costs: four bands, and a fifth case
Section 140B(3) charges additional income-tax on the aggregate of tax and interest payable, at a rate that depends on when the return is furnished. Act No. 7 of 2025 added the third and fourth bands:
| Furnished | Additional income-tax |
|---|---|
| After the time under 139(4) or 139(5) runs out, before twelve months from the end of the relevant AY | 25% |
| After twelve months, before twenty-four | 50% |
| After twenty-four months, before thirty-six | 60% |
| After thirty-six months, before forty-eight | 70% |
The Explanation to 140B(3) settles the obvious follow-up question: tax "shall include surcharge and cess, by whatever name called, on such tax".
There is now a fifth case. Section 140B(3A), inserted by Act No. 4 of 2026 with effect from 1 March 2026, increases the additional income-tax by a further ten per cent of the aggregate of tax and interest where the updated return is furnished in pursuance of a notice under section 148, within the period allowed by that notice.
For assessment year 2026-27, whose relevant assessment year ends on 31 March 2027, those bands fall on 31 March 2028, 2029, 2030 and 2031, and nothing may be furnished after the last of them.
The gap the Act leaves, and why it should stay a gap
Here is a hole worth knowing about, because a tool that papers over it will quietly overcharge or undercharge your client.
Section 139(8A) permits an updated return "at any time within forty-eight months". Section 140B(3)(i), the twenty-five per cent band, begins only "after expiry of the time available under sub-section (4) or sub-section (5) of section 139".
So for an updated return furnished before the belated or revised return window has closed, the Act permits the return and states no rate of additional tax for it.
The right answer is not to pick one. It is to say that the Act states no additional tax for an updated return filed before the time for a belated or revised return ends, and that the practical options are to file a belated or revised return instead, or to wait. A number produced for that case is somebody's guess wearing the clothes of a calculation.
The 139(4) and 139(5) end dates themselves have to be read as in force rather than remembered, incidentally: 139(5) was substituted by Act No. 4 of 2026.
Important
Any working that prints a figure for every date you give it, with no case where it declines, is not reading the provisions. It is interpolating.
Pay first, then file
Section 140B(1) and (2) require the return to be accompanied by proof of payment of the tax, additional income-tax, interest and fee. Clause (ca) of section 139(9) makes a return without that proof defective.
So the order is fixed: work out the challan, pay it, then write the paid challan details into the file. A return furnished before the payment is a defective return, which is a notice and a fifteen-day clock rather than a filing.
The computation splits in two:
Where no return was furnished earlier under 139(1) or 139(4), the tax payable on the updated return is taken after advance tax, deductions and collections at source, relief under sections 89, 90, 90A and 91 and credit under 115JAA and 115JD, plus interest and fee for the delay, plus the additional income-tax. Interest under 234A is computed on the tax on total income as declared in the updated return.
Where a return was furnished earlier under 139(1), (4) or (5), the base shifts: interest under 234B is computed on "assessed tax" as section 140B(4) defines it, and the interest already paid in the earlier return comes into the sum.
If the earlier return's figures are not in front of you, the second case cannot be computed at all. That is a reason to go and get them, not a reason to compute the first case instead.
Next year it is a different form under a different Act
The Income-tax Act, 2025 governs from 1 April 2026, and this is where practices will trip.
Rule 164(14) of the Income-tax Rules, 2026 says that where a return relates to the tax year commencing 1 April 2025 or any earlier tax year, it is furnished in the form applicable in that tax year. So an updated return for financial year 2025-26, or anything before it, is still Form ITR-U under sections 139(8A) and 140B. That is most of what a practice will file for the next few years.
From tax year 2026-27 the updated return becomes Form ITR-UN, under section 263(6) of the 2025 Act, with the tax under section 267 and the form prescribed by rule 165. Rule 166(1)(c) makes a return under 263(6) defective without the details of payment of tax as per section 267, which is the 139(9)(ca) rule carried across under new numbers.
Two Acts will be live in the same filing season, for different years, with different section numbers for the same ideas. That is the practical fact to plan around, and it is the same pattern as the TDS forms being renumbered and the 87A rebate becoming section 156.
- FY 2025-26 and earlier: Form ITR-U, sections 139(8A) and 140B of the 1961 Act
- FY 2026-27 onwards: Form ITR-UN, section 263(6) of the 2025 Act, tax under section 267
- The year decides the form, not the date you sit down to file it
Conclusion
An updated return is four years wide, costs between a quarter and seven tenths of the tax and interest on top, and is barred outright by facts only the client can tell you.
Every one of those is in the provisions. None of them is in the form's own heading, which still says twenty-four months, and several changed in the last two Finance Acts.
Greenote holds the rates, the windows and the bars as dated entries quoting the official text, so an entry that has not been verified against the source refuses to print a figure and leaves a gap with its reason instead. The file is built on your PC and you file it. See what the return workspace covers, or start with which ITR form the client can use.
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