Interest & Late Fee Calculator
Section 50 interest · Section 47 late fees · GSTR-1 / 3B / 9
Interest & Late Fee — Single Return
Computes Section 50 interest and Section 47 late fees with the post-2022 slab caps.
Illustration 1 — GSTR-3B filed 45 days late
Turnover ₹4 crore. GSTR-3B for May 2026 due 20-06-2026, actually filed 04-08-2026 (45 days late). Tax liability ₹5,00,000 of which ₹2,00,000 was paid in cash (balance set off from ITC).
Expected: Interest u/s 50(1) only on the ₹2,00,000 cash portion @18% for 45 days ≈ ₹4,438; late fee ₹50/day × 45 = ₹2,250 (within ₹5,000 cap).
Illustration 2 — Nil GSTR-1 delayed 90 days
Small trader, turnover ₹1.2 crore. Nil GSTR-1 for Q1 due 13-07-2026, filed 11-10-2026 (90 days late). No tax payable.
Expected: No interest (nil liability). Late fee ₹20/day × 90 = ₹1,800, restricted to the ₹500 nil-return cap.
Illustration 3 — GSTR-9 annual return late
Turnover ₹12 crore. GSTR-9 for FY 2025-26 due 31-12-2026, filed 20-02-2027 (51 days late).
Expected: Late fee ₹100/day × 51 = ₹5,100, subject to the 0.04% of turnover cap (₹4,80,000) — so ₹5,100 payable.
Figures are illustrative and meant for demonstration / training use.
| Delay (days) | 0 |
| Interest u/s 50 @ 18% × 0 days | ₹ 0 |
| Late fee gross (₹50/day) | ₹ 0 |
| Late fee cap | ₹ 2,000 |
| Late fee (after cap) | ₹ 0 |
| Total Challan Payable | ₹ 0 |
For GSTR-3B, Section 50(1) proviso restricts interest to the net cash component of the delayed liability. GSTR-1 has no tax-payment component — only Section 47 late fee applies. Late-fee caps shown reflect Notif 19/2021-CT, 22/2021-CT and 07/2023-CT slabs.