10 Common Mistakes to Avoid When Filing ITR for AY 2026–27

A tax return is only as good as the data and decisions behind it, and most of the trouble that taxpayers face later, such as refund delays, defective-return notices and mismatch alerts, traces back to a handful of avoidable slips. This year the stakes are a little higher. The income tax return for AY 2026-27 reports income earned in FY 2025-26, the regular 31 July 2026 deadline for non-audit taxpayers has already gone by, and the department now pre-fills far more information from banks, brokers and employers.

That leaves belated filing, available until 31 December 2026, as the main route for anyone who is yet to file. Knowing the ITR filing mistakes to avoid can save you money, stress and follow-up work. Below we walk through the ten errors we see most often in practice, explain why each one matters, and show how to fix it or prevent it. We also cover what to do if a mistake has already slipped into a filed return.

Why Do ITR Filing Mistakes Matter More for AY 2026–27?

ITR filing mistakes matter more for AY 2026-27 because most of your financial footprint is already visible to the Income Tax Department before you file, so inconsistencies are detected quickly and automatically. A small omission that went unnoticed a few years ago can now generate an intimation or a notice within months.

Three developments explain this. First, the Annual Information Statement collects interest, dividends, securities trades, mutual fund redemptions and property deals reported by third parties, and the department compares it with what you declare. Second, the new tax regime is the default, so anyone who files without a conscious choice may lose deductions they were counting on. Third, the original due date has passed for most individuals, which means any error discovered now must be corrected through a belated, revised or updated return, each with its own cost. A calm, step-by-step review before you click submit is therefore far cheaper than fixing the return afterwards. If you need a refresher on the filing process itself, read our guide to ITR filing for salaried employees.

What Are the 10 Most Frequent ITR Filing Errors in AY 2026–27?

The ten most frequent errors are skipping the AIS review, picking the wrong form, leaving out minor income, drifting into the wrong regime, claiming deductions you cannot support, mishandling capital gains, ignoring foreign assets, giving incorrect bank details, forgetting e-verification, and filing late without a plan. Here is how each one arises and how to avoid it.

1. Filing Without Reading the AIS.

   Many taxpayers file using only Form 16 and ignore the Annual Information Statement. The AIS lists savings interest, dividends, share trades and other third-party reported items that may not carry any TDS. Download it from the portal, check every line, and give feedback on wrong entries before you finalise the return.

2. Selecting an Unsuitable ITR Form.

   Each form has eligibility conditions. ITR-1 suits simple resident cases and cannot be used if you hold foreign assets, are a company director, or have gains beyond the permitted section 112A limit. ITR-2 covers most investors, while ITR-3 and ITR-4 are meant for business and professional income. A mismatch between income and form commonly ends in a defective return notice under section 139(9).

3. Ignoring Small and Passive Income Streams.

   Interest on a dormant savings account, dividends from a handful of shares, a month of freelance income or rent from a parent’s flat can all be taxable. Because no tax may have been deducted, they are easy to forget, yet they usually appear in the AIS. Report taxable items under the correct head, and show genuinely exempt income in the exempt-income schedule.

4. Letting the Default Regime Decide for You.

   The new regime applies automatically unless you choose otherwise. Salaried taxpayers can pick a regime each year, whereas people with business or professional income who leave the new regime must file Form 10-IEA. Run both calculations every year, because the cheaper option changes with your income and investments. Our comparison of the new regime and old regime for AY 2026-27 can help.

5. Claiming Deductions Without Documents or Eligibility.

   Sections 80C, 80D, HRA and home loan interest on a self-occupied property are generally tied to the old regime. Claiming them under the new regime, or claiming HRA without rent receipts, invites adjustments and queries. Collect proofs while you file and keep them handy for several years.

6. Getting Capital Gains Wrong.

   Taxpayers often mix up short-term and long-term holding periods, forget switches between mutual fund schemes, or overlook gains from ESOPs and property sales. Use broker and registrar statements, compute each sale separately, and choose a form that has the capital gains schedules. Our capital gain overview explains the basics.

7. Overlooking Foreign Assets and Income.

   Resident taxpayers who hold foreign bank accounts, overseas shares or stock awards from a foreign employer must disclose them in Schedule FA, even when no income was earned. Non-disclosure can attract a heavy penalty under the Black Money Act, so this is not an area for guesswork. See our note on the penalty for non-disclosure of foreign assets.

8. Giving Wrong or Inactive Bank Details.

   Refunds go only to a bank account that is pre-validated against your PAN. A closed account, a typing error, or a name mismatch can leave the refund stuck for weeks. Validate the account before filing and update any changed account details on the portal.

9. Not E-Verifying the Return.

   A return becomes valid only after verification. The current window is 30 days from the date of filing, and verification can be completed by Aadhaar OTP, net banking or a bank or demat-based option. Skipping this step means the return is treated as not filed, so make verification part of the same sitting.

10. Filing Late Without Checking the Cost.

    Late filing brings a fee under section 234F of ₹5,000, or ₹1,000 where total income is up to ₹5 lakh, plus interest under section 234A on unpaid tax. It can also forfeit the right to carry forward certain losses. Decide on a filing date early, arrange documents in advance, and do not leave the return to the last day.

How Can You Cross-Check AIS, TIS and Form 26AS Before Filing?

You cross-check them by downloading all three statements from the e-filing portal, comparing them line by line with your own records, and resolving every difference before you submit. This one habit prevents the majority of mismatch notices.

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Form 26AS is chiefly a statement of tax credits, showing TDS, TCS and tax you have paid. The AIS is broader and also reports interest, dividends, securities and mutual fund transactions and some high-value purchases, while the TIS condenses the AIS into category totals. Start with income: does every salary, interest and dividend figure in your return match the statements? Then check tax credits: is each TDS entry visible in 26AS, and are you claiming only what is shown? If an entry is wrong, such as a duplicate or a transaction belonging to someone else, submit feedback on the portal. If it is correct but differs from your figures, update your return rather than hoping it is ignored. For tax-saving and planning advice before you file, our tax health check service is a useful starting point.

What Can You Do If You Have Already Filed With an Error?

If you have already filed with an error, you can generally correct it by filing a revised return, replying to a defective-return notice, or, where the other routes have closed, filing an updated return. Which one works depends on timing and on the nature of the mistake.

A revised return replaces the original and is meant for omissions or wrong entries discovered after filing. The revised-return deadline for AY 2026-27 has been reported by some sources as 31 March 2027 following the latest budget amendments and by others as 31 December 2026, so check the portal for the date that applies to you. If the department finds your return defective, section 139(9) lets you respond within the stated time with corrected information. A belated return, available until 31 December 2026, is for those who missed the regular due date. After that, an updated return under section 139(8A), known as ITR-U, can be filed until 31 March 2031 but carries additional tax and cannot be revised again.

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If a notice has already arrived, respond within the time shown and keep supporting documents ready. Our team can help with income tax notice replies and with a defective return under section 139(9).

How Has Income Tax Return Filing in India Evolved?

Return filing in India has evolved from manual paper returns before 1991 to a largely digital, data-matched process, which is why errors are now spotted faster than ever.

What Should Your Pre-Filing Checklist Look Like?

Your pre-filing checklist should cover documents, statements, choices and follow-through, so that nothing is left to memory. Work through it before you open the utility and again before you submit.

When you compute tax under both regimes, remember that the rebate under section 87A can reduce tax on ordinary income to nil for eligible lower incomes; our guide to the Section 87A rebate for AY 2026-27 explains who qualifies. Taxpayers with business income, foreign assets or crypto holdings should consider specialist help; see our pages on ITR-3 return filing and NRI tax filing.

Frequently Asked Questions About ITR Filing for AY 2026–27