Estimate the late fee on a delayed GSTR-3B, GSTR-1 or GSTR-9 from the number of days late, before the statutory cap is applied.
Choose the return, enter the number of days between the due date and the date you actually file, and the tool multiplies the days by the per-day late fee. For GSTR-3B and GSTR-1 the lower figure is the nil-return rate (₹10 CGST + ₹10 SGST = ₹20 a day) and the higher figure is the rate for a return with tax liability or outward supplies (₹25 + ₹25 = ₹50 a day). For GSTR-9 the per-day rate depends on aggregate turnover.
Apply the cap yourself. Late fees stop at a maximum. For GSTR-3B and GSTR-1 the caps under the 2021 late-fee notifications are ₹500 for nil returns, ₹2,000 where the previous year's turnover was up to ₹1.5 crore, ₹5,000 for ₹1.5–5 crore and ₹10,000 above ₹5 crore (CGST + SGST together). For GSTR-9 the cap is a percentage of turnover in the state; see the late fee and interest guide.
Interest is separate. Interest under section 50 of the CGST Act runs at 18% a year on tax paid late in cash. Work it out as tax × 18% × days ÷ 365 and enter it in the interest box.
Worked example (illustrative). A regular GSTR-3B with ₹40,000 of net cash tax, filed 25 days late: late fee 25 × ₹50 = ₹1,250 (under the ₹2,000 cap for a small business); interest ₹40,000 × 18% × 25 ÷ 365 ≈ ₹493; total ≈ ₹1,743.
Limits. Late fee on IGST-only returns, waivers and amnesty notifications are not modelled. The GST Council's 57th meeting (October 2026) recommended a late fee waiver for small taxpayers who file within the month of the due date; check on the GST portal whether it has been notified.
Calculations and Checklists
How to calculate GST late fees per day and their caps for GSTR-3B, GSTR-1 and GSTR-9, interest at 18% under section 50, and how the 2026 rules and proposed waiver affect you.
Filing Mistakes, Notices and Sources
What happens when a business stops filing GST returns: e-way bill blocking, suspension, cancellation, the revocation route and time limits, the three-year bar and the costs of restarting.
Calculations and Checklists
Who must file GSTR-9 and GSTR-9C for FY 2025-26, the 31 December 2026 due date, how to reconcile books with returns table by table, late fees and what software and CAs charge.
Software Costs and 2026 GST Rules
How the QRMP scheme works for businesses up to ₹5 crore turnover, the fixed-sum and self-assessment payment methods, IFF for B2B customers, and whether quarterly filing really saves cost.
