ITR Filing Mistakes CA Firms Should Catch Before a Notice Arrives

Most income tax notices that land on a CA firm's desk do not start with the department. They start weeks or months earlier, with a return that went out with a small error nobody caught. The team at AskSolique, which builds research tools for Indian tax practices, sees the same pattern again and again: the itr filing mistakes that cause the most rework are rarely complex. They are mismatches, wrong forms and missed steps that a firm could have spotted with a disciplined pre-filing review.
This article walks through the errors that show up most often, why each one matters, and a simple review routine a firm can run before any return is submitted.
1. Filing on the wrong ITR form
Choosing the form looks routine, but it is one of the most common reasons a return is treated as defective. ITR-1 has narrow eligibility. It is not available where total income exceeds ₹50 lakh, where the individual is a director in a company, or where there is income that the form does not cover. Clients who picked up a property sale, a foreign asset or a business receipt during the year often still expect “the simple form” because that is what they filed last time.
A good habit is to confirm the form only after the full income picture is in front of you, not at the start of the engagement. Ask every client directly about capital gains, directorships, foreign holdings and any freelance or business income before the form is selected.
2. Not reconciling with AIS, TIS and Form 26AS
The department already knows a great deal about each taxpayer. Interest from savings accounts and fixed deposits, dividends, securities transactions, high-value purchases and TDS credits all flow into the Annual Information Statement and Form 26AS. When a return reports less than what these statements show, the processing system flags the gap, and an adjustment intimation under section 143(1) often follows.
The fix is unglamorous: download AIS, TIS and Form 26AS for every client and tick off each line against the computation. Where the AIS is wrong, for example a duplicated entry or a transaction that belongs to someone else, submit feedback on the portal and keep a record. If an intimation does arrive, this note on replying to a 143(1) demand notice sets out a practical response checklist.
3. Picking the wrong tax regime, or forgetting the regime has changed
Since the new regime under section 115BAC became the default, a return filed without an active choice is computed under it. That matters because most Chapter VI-A deductions, such as those under sections 80C and 80D, are not available in the new regime. Clients who have paid insurance premiums or made tax-saving investments sometimes assume the deductions will apply automatically, and then question the computation later.
The other side of the same problem is a client with business income who opted out of the new regime in an earlier year. The rules on switching back and forth are stricter for business taxpayers than for salaried individuals, so a firm should check the history before changing the election.
4. Under-reporting small income items
Savings bank interest, interest on income tax refunds, small dividend amounts and income from minor children that has to be clubbed are easy to miss because each figure is small. Individually they rarely change the tax payable by much, but each one is a mismatch against AIS, and mismatches are what trigger automated scrutiny.
Capital gains deserve particular care. Transactions in mutual funds and listed shares appear in the AIS with sale values, but the cost of acquisition and holding period still have to be worked out properly. Since the changes to capital gains rates and holding periods in recent years, older templates may compute the wrong rate for a transaction, so it is worth checking the dates on every sale.
5. Missing the e-verification and refund basics
A return is not complete until it is verified. The time limit for e-verification is 30 days from filing, and a return verified late is treated as filed on the date of verification, which can bring a late fee and lost interest. This is one of the most avoidable errors on the list, yet it happens every season when a client is travelling or does not have access to the registered mobile number.
Refunds have their own trap. The bank account must be pre-validated on the portal and linked to the PAN, or the refund will fail even when the return is processed correctly. A quick check of the bank account status before filing saves weeks of follow-up.
6. Leaving foreign assets and directorships out
Resident taxpayers who hold foreign bank accounts, shares under an employer stock plan or any other foreign asset need to report them in Schedule FA, even if no income arose from them during the year. Leaving this schedule blank can attract penalties under the Black Money Act that are far larger than any tax involved. Employees of multinational companies who receive RSUs are the group most likely to miss this, often because they do not see the shares as “foreign”.
Directorships and unlisted shareholdings also have their own disclosure fields, and leaving them out is one of the reasons a return may be treated as defective.
Why the timing matters this year
Returns for financial year 2025-26 are still filed under the Income-tax Act, 1961, but the new Income Tax Act 2025 applies from 1 April 2026 and changes both the section numbering and some of the terminology firms use every day, starting with “tax year” in place of “previous year” and “assessment year”. For a while, teams will be working across both laws at once: old sections for returns and notices for past years, new sections for current-year advice. A clear Income Tax Act 2025 section mapping helps staff cite the right provision in computations and replies, and avoids a mistake of a different kind: quoting a section that no longer applies.
Where a mismatch has already turned into a full scrutiny case, the approach changes from correction to documentation. This guide to preparing a defensible response to an income tax scrutiny notice covers that stage in detail.
A pre-filing review routine for CA firms
The most reliable way to cut errors is a short, fixed checklist that a second person runs before any return is submitted:
- Confirm the ITR form only after the full income picture is known.
- Reconcile every AIS, TIS and Form 26AS line against the computation, and record any feedback submitted.
- Confirm the regime choice in writing with the client, and check the history for business taxpayers.
- Check capital gains dates, holding periods and rates transaction by transaction.
- Verify Schedule FA, directorships and unlisted shares.
- Confirm the refund bank account is pre-validated.
- Diary the e-verification deadline and follow up within the week.
Firms that also need fast answers on less common questions, such as how a particular deduction interacts with the new regime or how tribunals have treated a type of mismatch, increasingly use research tools alongside the checklist. Choosing the best AI tool for tax research in India comes down to whether it cites real provisions and case law you can verify, and AskSolique is built for that kind of work in CA practices. There is more on where these tools help and where they do not in this piece on where AI saves time in a CA firm, and where it does not.
Final word
None of these mistakes needs specialist knowledge to prevent. They need a routine, a second pair of eyes and a habit of reconciling with the department's own data before filing. Firms that build that routine spend far less of the year answering notices and far more of it advising clients.
To see how AskSolique supports income tax research and notice work for CA firms, you can contact the AskSolique team.
