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GST Interest & Late Fee Calculator

Filed GSTR-3B late? Estimate the interest on unpaid tax and the late fee, so there are no surprises when you file.

Reviewed 27 September 2026By Viraj SarfareFormula shown belowRuns in your browser
₹
days
1 days365 days
Type of return
Annual turnover
Estimated interest + late fee
₹1,493
20 days late
Interest at 18% a year₹493
Late fee (CGST + SGST)₹1,000
Late fee per day₹50 (₹25 CGST + ₹25 SGST)
Late fee cap applied₹2,000

What happens when GSTR-3B is late

Filing your GSTR-3B return after the due date triggers two separate charges. Interest is charged at 18% a year on the net tax you pay in cash, for each day it's late. A late fee is charged per day of delay, split equally between CGST and SGST (or charged as IGST), up to a maximum that depends on your turnover and whether the return has any tax.

FORMULAS
Interest = net cash tax × 18% × days late ÷ 365 Late fee = ₹50 per day (₹20 for nil returns), capped

Worked example

With ₹50,000 of net GST payable and a delay of 20 days, interest is about ₹493 and the late fee is ₹1,000. That's ₹1,493 on top of the tax itself.

Late fee caps (GSTR-3B)

SituationMaximum late fee per return
Nil return (no tax, no outward supplies)₹500
Turnover up to ₹1.5 crore₹2,000
Turnover ₹1.5–5 crore₹5,000
Turnover above ₹5 crore₹10,000

These are the caps notified in 2021 and still widely applied. Late fee rules are sometimes waived or changed by notification, so confirm on the GST portal, which calculates the actual fee when you file.

GSTR-1 is separate

This calculator covers GSTR-3B, the return where tax is actually paid. GSTR-1, the statement of sales, has its own late fee on similar per-day rates and caps, but no interest because no tax is paid through it. A late GSTR-1 also delays your customers' input tax credit, which hurts B2B relationships more than the fee itself.

Avoiding late fees

  • Know your due date: monthly filers typically file by the 20th of the next month; quarterly (QRMP) filers have staggered dates by state.
  • File nil returns on time too: nil returns attract late fees if missed. Many can be filed by SMS.
  • Pay what you can: interest applies only to unpaid tax, so paying on time and filing a few days later limits the cost.
  • Keep books up to date monthly: the most common cause of late filing is chasing invoices at the last minute. The GST invoice generator helps keep billing tidy.

Frequently asked questions

What is the late fee for GSTR-3B?

₹50 per day (₹20 per day for nil returns), split between CGST and SGST, subject to caps based on turnover. The portal calculates the exact amount when you file.

Is interest charged on the full tax or net tax?

On the net tax liability paid in cash, after using input tax credit.

Can late fees be waived?

The government has announced amnesty schemes and waivers at times. Check current notifications on the GST portal.

Official references: GST portal · CBIC – GST

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