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GSTR-3B late fee & interest calculator

A late GSTR-3B costs two separate things, computed two different ways. Enter three facts and see both — the late fee and the interest — with the total a late filing really carries.

For a monthly GSTR-3B, the 20th of the following month.

Delay is counted from the day after the due date up to this date.

The cash portion actually delayed — the net liability after input tax credit, not the gross output tax.

Days late—
Late fee — ₹50/day, capped at ₹10,000—
Interest — 18% per year on the tax paid late—
Total cost of the delay—

The two charges, in words

The late fee prices the late return. It is ₹50 for every day between the due date and the day the return is filed, and it stops growing at ₹10,000 per return — the cap is reached at 200 days. The fee is charged per return, so a business registered in three states can owe it on each state’s GSTR-3B separately. It applies even if the tax itself was paid on time: it prices the late filing, not the late money.

The interest prices the late money. Tax that should have been paid by the due date but is paid late carries interest at 18% per year, pro-rated for the days of delay: tax delayed × 18% × (days delayed ÷ 365). Interest runs on the net liability actually discharged in cash — after input tax credit — and unlike the fee it has no cap: it keeps accruing until the tax is paid.

A worked example, the same one our guide uses: a return due on 20 November, filed and paid on 2 December — 12 days late — with a net tax liability of ₹2,00,000. The late fee is 12 × ₹50 = ₹600. The interest is ₹2,00,000 × 18% × 12 ÷ 365 ≈ ₹1,184. Total cost of the delay: ≈ ₹1,784. Try it above — the calculator is pre-filled with last month’s dates so you can change any one input and watch the two charges move independently.

For the full reasoning — why the two charges rank differently, and when the interest becomes the bigger problem — read the guide: GSTR-3B late fee and interest, actually calculated. The MCA side has its own meter: see the MCA additional-fee calculator.

Metiq builds every client’s GSTR-3B deadline into one calendar and prices the delay on anything overdue, so this arithmetic happens before the due date, not after it — start the free trial.

General information only — not professional advice.