Section 234A imposes interest at 1% per month or part of a month on the tax liability outstanding from the due date until the date of filing.

If you missed the September 16, 2025, deadline to submit the income tax return (ITR) for AY 2025-26, you can still file. But, it comes at a cost — a late-filing fee, interest on any unpaid tax, and the risk of losing some tax benefits. The window for filing a belated return this year runs only until December 31, 2025, so acting quickly will limit additional interest and penalties.

How much is the late fee?

Section 234F of the Income Tax Act prescribes a late-filing fee of Rs 5,000 for returns filed after the due date. However, if your annual income is below Rs 5 lakh, the late fee is capped at Rs 1,000.

Apart from the late fee, you must pay interest on any unpaid tax. Section 234A imposes interest at 1% per month or part of a month on the tax liability outstanding from the due date until the date of filing. Interest is computed on the balance tax (tax payable after accounting for TDS, TCS and advance tax).

For example, if you owe Rs 50,000 in tax and file three months late, interest under Section 234A would be Rs 50,000 × 1% × 3 = Rs 1,500, in addition to the late fee. If advance tax instalments were short or unpaid, additional interest under Sections 234B and 234C may also apply.

There are non-monetary costs too. Filing a belated return may mean you lose the right to carry forward certain kinds of losses to future years. In practice, that usually means business losses and capital losses cannot be carried forward if the return for the year in which the loss arose is filed late.

If you are owed a refund, filing late does not forfeit the refund itself, but it can delay processing. The income tax department processes refunds after the return is filed and verified; a belated return only restarts that clock. Also, bear in mind that certain features, like switching tax regimes or claiming some deductions, can be restricted or complicated after the original due date, so check the rules that apply to your form and income profile before filing.

What you should do right now

First, calculate your tax liability accurately for the year, accounting for TDS, TCS and any advance tax already paid. If there is tax due, pay the self-assessment tax and any interest before filing — the return will show the tax paid and the portal will accept it. Compute interest under Section 234A (1% per month) from the day after the original due date to the date you file, and include that payment while submitting the belated return.

Next, complete and file the appropriate ITR form online and e-verify the return immediately; an unverified return is treated as if it has not been furnished. The Income Tax Department’s FAQs describe accepted e-verification methods and timelines. Keep receipts of tax payments and verification for your records.

Can you revise a belated return if you spot an error? Yes, a belated return can be revised.

If you miss September 16, file before December 31 to remain compliant for this assessment year. Yes, you will likely pay a late fee and interest at 1% per month on unpaid tax, and you may lose the right to carry forward certain losses. If you are due a refund, file the belated return and e-verify. Refunds are processed only after the return is filed and verified.