MetiqAsk ten business owners what a late GSTR-3B costs and you will get ten vague answers — "some penalty", "18% something", "₹50 a day, I think". The vagueness is expensive: firms cannot prioritise a filing they cannot price. So here are the two charges, separated, with the arithmetic done in the open.
A late GSTR-3B attracts two independent charges. They are computed differently, capped differently, and triggered by different things. Confusing them is how a ₹600 problem gets described as a disaster — and how a genuinely large interest bill gets missed.
The two charges at a glance
| Charge | Rate | Cap | Triggered by |
|---|---|---|---|
| Late fee | ₹50 per day of delay | ₹10,000 per return | Filing the return late |
| Interest | 18% per year | No cap | Paying the tax late |
The standard due date for a monthly GSTR-3B is the 20th of the following month. Delay is counted from the day after the due date until the return is filed (for the fee) and until the tax is paid (for the interest).
The late fee: ₹50 a day, ₹10,000 at most
The late fee is simple arithmetic:
Late fee = ₹50 × number of days delayed, subject to a maximum of ₹10,000.
Worked examples:
- Filed 6 days late: 6 × ₹50 = ₹300.
- Filed 12 days late: 12 × ₹50 = ₹600.
- Filed 40 days late: 40 × ₹50 = ₹2,000.
- Filed 200 or more days late: the fee stops growing at ₹10,000 — the cap is reached at 200 days.
Two things to notice. First, the fee is per return: a business registered in three states files three GSTR-3Bs and can owe the fee on each. Second, the fee depends only on the filing date. If the tax itself was paid on time through the electronic cash ledger but the return was filed late, the late fee still applies — it prices the late return, not the late money.
Interest: 18% per year on the tax paid late
Interest prices the late money. If tax that should have been paid by the due date is paid late, interest runs at 18% per annum on the delayed amount for the days of delay:
Interest = tax delayed × 18% × (days delayed ÷ 365)
Worked examples:
- Tax of ₹1,00,000 paid 10 days late: ₹1,00,000 × 18% × 10 ÷ 365 = ≈ ₹493.
- Tax of ₹2,00,000 paid 12 days late: ₹2,00,000 × 18% × 12 ÷ 365 = ≈ ₹1,184.
- Tax of ₹5,00,000 paid 45 days late: ₹5,00,000 × 18% × 45 ÷ 365 = ≈ ₹11,096.
Unlike the late fee, interest has no cap — it simply keeps accruing until the tax is paid. This is why the two charges rank differently: a short delay on a small liability is a fee problem of a few hundred rupees, while a long delay on a large liability is an interest problem that dwarfs the fee. The 12-day example above makes the point: the fee is ₹600 and capped forever; the interest on ₹2,00,000 is already ₹1,184 and still running.
One relief built into the computation: interest is charged on the tax actually delayed — the net liability discharged through the cash ledger, after input tax credit is applied — not on the gross output tax of the month.
Putting them together
A monthly filer due on 20 November files and pays on 2 December — 12 days late — with a net tax liability of ₹2,00,000:
- Late fee: 12 × ₹50 = ₹600
- Interest: ₹2,00,000 × 18% × 12 ÷ 365 = ≈ ₹1,184
- Total cost of the delay: ≈ ₹1,784
Paid a month later still, the fee stays ₹600 for those same 12 days only if the return was filed — if both filing and payment slip to 45 days, the fee rises to ₹2,250 and interest to roughly ₹4,438, a total near ₹6,688. Delay compounds quietly, which is precisely why it is worth computing rather than guessing.
Run the same arithmetic on your own figures in the GSTR-3B late-fee and interest calculator — due date, filing date and net tax in; fee, interest and total out. Or skip the arithmetic entirely: Metiq prices this delay on every client's overdue filings automatically, which is most of the point of how it is priced.
FAQ
Is the late fee charged per day or per return?
Both, in effect: ₹50 per day of delay, per return, capped at ₹10,000 per return. A multi-state registration can owe it on each state's return separately.
If I pay the tax on time but file the return late, is there interest?
Interest follows the money: tax paid on time attracts no interest. The late fee still applies, because the return itself was late.
Does interest apply on the full output tax or the net liability?
On the net tax liability actually discharged in cash — after input tax credit. If most of the month's liability is covered by credit, the interest base is only the cash portion that was delayed.
Can the late fee or interest be waived?
Amnesty and waiver schemes are announced from time to time by CBIC notification and apply to specified periods and conditions. Outside such a scheme, both charges are computed by the portal as above — do not plan a filing calendar around a waiver that has not been announced.
What is the cheapest day to be late?
There isn't one. The fee starts the day after the due date and interest starts with it. The economics argue for a boring conclusion: the return that is filed on the 20th costs nothing extra at all.
Metiq builds every client's GSTR-3B deadline — and the documents it depends on — into one calendar, and prices the delay on anything overdue, so a late filing is a number your firm sees, not a surprise your client forwards.
General information only — not professional advice.