The short version: The ₹5,000 fee under Section 234F is real but small. The warning that you will be forced onto the new regime is true and, for most filers, worth nothing — below ₹12 lakh of income the new regime already wins, so there is nothing to lose. The consequence that actually costs money is Section 80: business, speculative and capital losses you fail to file on time can never be carried forward, in any later year, by any means.
Whose deadline this is
31 August 2026 applies to non-audit filers of ITR-3 and ITR-4 — freelancers, consultants, doctors, lawyers, individual proprietors, and anyone under the presumptive schemes in Sections 44AD, 44ADA and 44AE. The Finance Act 2026 moved this date permanently, so it is not the annual extension people have learned to wait for.
Salaried filers on ITR-1 and ITR-2 had 31 July 2026, and that has already passed. If that is you, everything below already applies — skip to what you can still do. Audit cases run to 31 October. The full calendar, and why the deciding factor is your audit position rather than your form number, is in our breakdown of the split calendar.
Cost one: the late fee, and it is capped
Section 234F charges a flat ₹5,000 for filing after the due date. If your total income does not exceed ₹5 lakh, the fee cannot exceed ₹1,000. There is no sliding scale between the two and no proportionality to how late you are — one day past the deadline costs exactly what four months past costs.
It is a fixed, known, survivable number. Treat it as the price of the delay, not as the reason to panic.
Cost two: interest, which does scale with delay
Section 234A charges 1% per month or part month on unpaid tax, running from the due date until you actually file. "Part month" matters: filing on 1 September rather than 31 August triggers a full month of interest, not a day of it.
The important qualifier is that this runs on unpaid tax. If your TDS and advance tax already cover your liability — the common case for salaried filers, and for professionals who paid their instalments — there is nothing outstanding for 234A to charge on, and this cost is zero however late you file. If you do have a balance, the advance tax calculator shows how 234A and 234C stack, since they are cumulative rather than alternatives.
Cost three: the old-regime warning, computed rather than repeated
This is the one every filing-season article leads with, usually in capitals. The rule is real: under Section 115BAC, the option to leave the new regime must be exercised on or before the Section 139(1) due date, and for business and professional income that means Form 10-IEA filed by the deadline. File late and the option is gone for that year. A revised return will not restore it and rectification will not be entertained.
The question nobody answers is what that actually costs. So we ran it, using the same slabs, rebate and cess as our regime calculator, to find the point at which the old regime is genuinely the better choice:
| Gross income | New regime tax | Old regime only wins if deductions exceed |
|---|---|---|
| ₹8,00,000 | ₹0 | never — new regime cannot be beaten |
| ₹10,00,000 | ₹0 | never |
| ₹12,00,000 | ₹0 | never |
| ₹13,00,000 | ₹66,300 | ₹4,94,000 |
| ₹15,00,000 | ₹97,500 | ₹5,44,000 |
| ₹20,00,000 | ₹1,92,400 | ₹7,09,000 |
| ₹25,00,000 | ₹3,19,800 | ₹8,01,000 |
Below ₹12 lakh, losing the old-regime option costs you precisely nothing. The new regime's ₹75,000 standard deduction and rebate take the bill to zero, and no quantity of deductions under the old regime can beat zero. For a very large share of the people being warned about this, the warning is empty.
Above that it becomes real but demanding. At ₹15 lakh you need more than ₹5,44,000 of deductions before the old regime pulls ahead. Maxed Section 80C at ₹1.5 lakh, 80D at ₹25,000, the ₹50,000 NPS addition under 80CCD(1B) and ₹2 lakh of home loan interest together come to ₹4.25 lakh — still short. You need a substantial HRA exemption on top before the old regime wins at all, and at the crossover point on ₹15 lakh the margin is ₹260.
So the honest position: if you are a high earner with a large rent claim and a home loan, this is a genuine and expensive loss, and it is reason enough on its own to file on time. If you are most people, it is a rounding error being sold as a catastrophe. Check which you are with the crossover analysis before deciding how hard to sprint.
The one that is genuinely permanent
Section 80 is where the real damage sits, and it gets a fraction of the attention. File after the Section 139(1) due date and you forfeit the right to carry forward:
- Business losses
- Speculative business losses
- Capital losses, short-term and long-term
- Losses from owning and maintaining race horses
Forfeited means gone. Not deferred, not claimable later, not recoverable through a revised return in a subsequent year. A return filed one day late loses the entire carry-forward benefit for that year of losses.
For anyone who took a bad year in the markets, or a loss-making first year in business, this dwarfs everything above. A ₹6 lakh capital loss that could have sheltered gains across the next eight assessment years is worth far more than ₹5,000 — and unlike the late fee, no later payment buys it back.
Two exceptions survive a late filing, and they are worth knowing: loss from house property can still be carried forward, and so can unabsorbed depreciation. Section 80 does not reach either.
A confusion worth clearing up: which Act you are filing under
The Income-tax Act, 2025 came into force on 1 April 2026, and a reasonable person filing a return in August 2026 assumes it governs what they are doing. It does not.
The return you are filing now is for FY 2025-26 — income earned up to 31 March 2026 — and that income remains governed by the Income-tax Act, 1961. The date you physically file does not change which legislation applies to the period being reported. Every section number in this article is a 1961 Act section for that reason, and those are the ones that will appear on your intimation.
What the 2025 Act governs is the year you are living through now, which you will file next year. For the changes that are coming rather than the rules you are filing under, see what the new Act actually changes.
What you can still do
A belated return under Section 139(4) can be filed up to 31 December 2026, or before the assessment is completed, whichever comes first. That window is not extendable and it is the last ordinary route in.
Filing belated still gets you most of what matters. Your refund is still payable if one is due. TDS credit is not lost. House property loss carry-forward survives. What you cannot recover is the old-regime election and the Section 80 carry-forwards.
The practical order, if the deadline is close and you are not ready: pay the tax first, file second. Section 234A interest runs on unpaid tax, so a payment made now stops that meter even if the return itself takes another fortnight. And if you are not certain which form applies to you, or whether your accounts are liable to audit, settle that before anything else — the ITR form selector resolves both, and your deadline follows from the answer.