It depends on which version of s.149 your notice is under. Up to 31 August 2024 the escaped income had to be "represented in the form of" an asset, expenditure in respect of a transaction or in relation to an event or occasion, or an entry in the books - and s.149(1A) dealt expressly with a single asset or expenditure spread over more than one year. From 1 September 2024 the language is looser and there is no equivalent of s.149(1A). No decision was found requiring the s.148A order to set out the arithmetic.
Start by fixing the date of the notice, because s.149 has been rewritten twice and the two versions ask different questions.
For a notice issued on or after 1 September 2024, s.149 as substituted by the Finance (No. 2) Act 2024 (Act 15 of 2024) provides that no notice under s.148 shall be issued "(a) if three years and three months have elapsed from the end of the relevant assessment year, unless the case falls under clause (b); (b) if three years and three months, but not more than five years and three months, have elapsed from the end of the relevant assessment year unless the Assessing Officer has in his possession books of account or other documents or evidence related to any asset or expenditure or transaction or entries which show that the income chargeable to tax, which has escaped assessment, amounts to or is likely to amount to fifty lakh rupees or more." Section 149(2) applies the same architecture to the show-cause notice under s.148A at three years and five years, and there the test is whether the escaped income "as per the information with the Assessing Officer, amounts to or is likely to amount to fifty lakh rupees or more".
For a notice issued between 1 April 2022 and 31 August 2024, the test was narrower. The extended limb ran up to ten years and applied only where the officer had "books of account or other documents or evidence which reveal that the income chargeable to tax, represented in the form of - (i) an asset; (ii) expenditure in respect of a transaction or in relation to an event or occasion; or (iii) an entry or entries in the books of account, which has escaped assessment amounts to or is likely to amount to fifty lakh rupees or more". The Explanation to that version defined "asset" to include "immovable property, being land or building or both, shares and securities, loans and advances, deposits in bank account".
One transaction straddling two years was dealt with expressly in that version. Section 149(1A), inserted by the Finance Act 2022 with effect from 1 April 2022, applied where the income chargeable to tax represented in the form of an asset or expenditure in relation to an event or occasion "has been made or incurred, in more than one previous years relevant to the assessment years within the period referred to in clause (b)", and provided that a notice under s.148 shall be issued for every such assessment year. Read with the clause it qualifies, that is a rule about one asset or one expenditure whose value crosses fifty lakh rupees and whose making or incurring is spread over years: the threshold is tested on that asset or expenditure, and each of the years it spans may then be reopened. It is not a licence to add together unrelated escapements from different years until fifty lakh rupees is reached; the threshold in the opening words is tied to the relevant assessment year. The current version carries no equivalent of s.149(1A) - the officer's material now need only be "related to" an asset, expenditure, transaction or entries "which show" escapement of fifty lakh rupees or more for the year in question.
Whether disallowances and interest count is really a question about the words "represented in the form of". Under the pre-September 2024 limb the escaped income had to take one of three forms, and a disallowance does not obviously take any of them. The Delhi Tribunal is reported in ACIT v. M/s. JKM Infra Projects Ltd (ITA No. 3031/Del/2025) to have held, of a notice for AY 2013-14 alleging bogus purchases, that "the second condition prescribed thereon that such escaped income should be represented in the form of an asset is not satisfied herein, as disallowance of expenditure cannot be construed as being represented in the form of an asset", and to have quashed the reopening as time-barred. That report is on one host only and I could not corroborate it, so use it as an argument rather than as a citation. Note also that the argument is weaker after 1 September 2024: the current limb does not require the income to be represented in the form of anything, only that the material be related to an asset, expenditure, transaction or entries which show the escapement. I found no decision on the current wording.
Interest is a different question again, and one nothing I reached answers. Where the alleged escapement is interest income not returned, that is income and there is no obvious reason it should not count. Where the figure the officer has arrived at includes interest charged under ss.234A to 234C on a proposed addition, that is not escaped income at all and should be taken out of the computation before the threshold is tested. Neither proposition is supported here by authority.
On whether the s.148A order must itself set out the computation, the statute takes you only so far. Section 148A(3) requires that the Assessing Officer "shall, on the basis of material available on record and taking into account the reply of the assessee furnished under sub-section (2), if any, pass an order with the prior approval of the specified authority determining whether or not it is a fit case to issue notice under section 148". Section 149(2) fixes the threshold by reference to what the information with the officer shows. Together those require the officer to have material that shows fifty lakh rupees or more and to decide on the material on record; they do not in terms require the order to display an arithmetic working. I could not find a decision holding that a bare assertion that the limb applies is insufficient. The nearest support in this library is the line requiring the underlying material to be given to the assessee - Charu Chains & Jewels and Chotanagpur Diocesan Trust - which gets you the material from which the computation can be tested, but is not authority that the order must contain the computation.
For any year where the ordinary period has run, the fifty lakh figure is the only thing keeping the notice alive, so it is the first thing to attack and it is attacked on the department's own numbers. Getting the version of s.149 right matters as much as the arithmetic: an argument built on "represented in the form of an asset" is a good argument against a 2023 notice and a much weaker one against a 2025 notice, because Parliament removed those words.
The only thing behind my reopening notice is the Valuation Officer's report. Is that enough?
My return was only processed under 143(1). Does that stop the department reopening it later?
I made unexplained investments after the close of my accounting year. Which year can the officer tax them in, and can he reopen an earlier year to do it?
My land was notified and an award was made under the Land Acquisition Act, but I thought the award was too low, negotiated a higher figure and executed a sale deed. The Assessing Officer now says that was a voluntary sale and denies s.10(37). Is he right?
How much am I actually required to disclose — and can they reopen because the officer drew the wrong conclusion?
The sanctioning authority just wrote 'yes' and signed. Is that a sanction?
A reassessment was done in between. Does the two-year clock for s.263 restart from it?
I placed all my primary facts before the officer and he dropped the proceedings. Can a later officer reopen the assessment because he takes a different view of those same facts?
Every page in this library links to what it was written from, so you can check it rather than take our word for it.