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Free GST late fee and interest calculator

Short answer

A late GSTR-3B or GSTR-1 costs ₹50 a day (₹25 CGST + ₹25 SGST), or ₹20 a day for a nil return, capped per return at ₹2,000, ₹5,000 or ₹10,000 by last year's turnover (₹500 for nil). Tax paid in cash after the due date also carries 18% a year interest, day-wise, with no cap. Enter your dates below.

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  • Offline after first load
  • No data sent anywhere
  • CGST / SGST split
Return

GST late fee by days late and turnover

Late fee per return, CGST and SGST together, for GSTR-3B and GSTR-1. Interest is extra and depends on your tax.

Days late Nil return Up to ₹1.5 crore₹1.5 crore to ₹5 croreAbove ₹5 crore
5 ₹100 ₹250₹250₹250
10 ₹200 ₹500₹500₹500
30 ₹500 ₹1,500₹1,500₹1,500
60 ₹500 ₹2,000₹3,000₹3,000
100 ₹500 ₹2,000₹5,000₹5,000
200 ₹500 ₹2,000₹5,000₹10,000
Cap ₹500 ₹2,000₹5,000₹10,000

The rules the calculator uses

  • Late fee (Section 47, CGST Act): ₹50 a day — ₹25 CGST + ₹25 SGST — from the day after the due date to the day you file.
  • Nil return: ₹20 a day (₹10 + ₹10), capped at ₹500 in total.
  • Caps (CGST Notifications 19/2021 for GSTR-3B and 20/2021 for GSTR-1): ₹2,000 per return up to ₹1.5 crore turnover, ₹5,000 up to ₹5 crore, ₹10,000 above.
  • Interest (Section 50): 18% a year, day-wise, on tax paid in cash after the due date. No cap.
  • Usual due dates: GSTR-1 on the 11th (13th for quarterly QRMP filers), GSTR-3B on the 20th (22nd or 24th for QRMP, by state). Check the GST portal for extensions.

Annual returns (GSTR-9) and composition returns (GSTR-4) follow different caps — see our guide to GST late fees and interest. The portal's own computation is final; this page is a planning figure, not tax advice.

Who this calculator is for — and who should skip it

Use it if…

  • You run a GST-registered shop or trading business, missed a GSTR-3B or GSTR-1 date, and want the cost before you log in to the portal.
  • You are deciding whether to pay the cash tax today or next week, and want to see what each day of interest costs.
  • You are an accountant or CA explaining a client's late fee in rupees.

Skip it if…

  • You need the late fee on GSTR-9, GSTR-4 or GSTR-10 — the caps differ; read the late fees guide.
  • You have claimed excess input tax credit — that interest is 24% a year and needs your CA.
  • You keep missing due dates because the books are not ready. That is billing software with GSTR-1 and GSTR-3B reports, and ours is ₹399 a month per app with unlimited users.

Put this calculator on your own site

This page is free to link to, quote and recommend — in a blog post, a forum answer, a WhatsApp group or a client note. No permission needed and no attribution required: https://399apps.com/tools/gst-late-fee-calculator/

FAQ

Questions people ask about GST late fees

I filed my GSTR-3B 10 days late with ₹40,000 of tax to pay in cash — how much do I owe on top? +
A late fee of 10 days × ₹50 = ₹500 (₹250 CGST + ₹250 SGST), plus interest of ₹40,000 × 18% × 10 ÷ 365 = ₹197.26. Together about ₹697.26. The GST portal adds the late fee to your next return and computes the interest itself; this calculator shows you the figure before you file.
My business had no sales this month — do I still pay a late fee if I file the nil return late? +
Yes. A nil GSTR-3B or GSTR-1 filed late costs ₹20 a day (₹10 CGST + ₹10 SGST), capped at ₹500 in total per return. There is no interest, because there is no tax to pay late. Filing the nil return by the due date costs nothing.
Does the GST late fee keep growing forever if I do not file? +
No. The late fee stops at a cap per return set by last year's aggregate turnover: ₹2,000 up to ₹1.5 crore, ₹5,000 from ₹1.5 crore to ₹5 crore, and ₹10,000 above ₹5 crore (₹500 for a nil return). Interest has no cap — it keeps running at 18% a year on the unpaid cash tax until you pay.
Is interest charged on the full tax in my GSTR-3B or only on part of it? +
Only on the part paid in cash after the due date. Tax you set off from input tax credit carries no interest under Section 50 of the CGST Act. Enter the cash portion of your liability in the calculator, not the gross tax.
I filed GSTR-1 late — is there interest on that too? +
No. GSTR-1 reports your sales; it does not pay tax, so a late GSTR-1 carries only the late fee. Interest attaches to the tax paid through GSTR-3B. Your buyers' input credit is still delayed when GSTR-1 is late, which is the cost they notice.
Is anything I type into this GST late fee calculator sent to a server or saved? +
No. It runs entirely in your browser. Nothing you enter is sent anywhere or stored — no account, no log. Close the tab and the numbers are gone.
Never pay the late fee in the first place

Billing software that has GSTR-1 and GSTR-3B ready before the due date

Nidhi Books by 399Apps builds your GSTR-1 and GSTR-3B figures from the invoices you already raise, so filing is a review, not a scramble — flat ₹399 per month per app, unlimited users, cloud or self-hosted.

See pricing Free GST calculator