GST Late Fee & Interest Calculator

Late fee versus interest: two separate charges

A delayed GST return triggers two different amounts. The late fee under Section 47 is a fixed daily charge for filing the return late, whether or not any tax was due. Interest under Section 50 is 18% a year on the tax you paid after the due date. File a nil return a month late and you owe a late fee but no interest. Pay ₹5 lakh of tax a month late and you owe both.

The portal computes the late fee automatically when you file, but it does not stop you from being surprised. This calculator lets you see the number before you log in, so you can tell a client what a delayed filing will actually cost and whether to pay now or wait for an amnesty.

How the calculator works

• Pick the return: GSTR-3B, GSTR-1, GSTR-4 or GSTR-9.
• Enter the due date and the date you filed, or plan to file.
• Tick “nil return” if there was no outward supply and no tax; the daily fee drops to ₹20.
• Choose the turnover bracket for the previous financial year; this sets the cap.
• Enter the net tax paid late to get the 18% interest for the same number of days.

Example

GSTR-3B for March 2025 was due on 20 April 2025 and filed on 10 May 2025, 20 days late, with ₹1,00,000 of net tax paid on filing. Late fee is 20 × ₹50 = ₹1,000 (₹500 CGST + ₹500 SGST), under the ₹2,000 cap for a small taxpayer. Interest is ₹1,00,000 × 18% × 20/365 = ₹986. Total cost of the delay: about ₹1,986.

Points from practice

• Late fee is per return, so a client who missed six months of GSTR-3B and GSTR-1 faces twelve separate fees.
• GSTR-1 fee is debited when the next GSTR-3B is filed, which catches clients off guard.
• Late fee is paid in cash through the electronic cash ledger; ITC cannot be used for it.
• If a GSTR-3B is pending, GSTR-1 for the next period cannot be filed, so the delays compound.
• Composition dealers filing GSTR-4 after the due date pay ₹50 a day capped at ₹2,000 (₹500 for nil).

GST late fee caps (per return, CGST + SGST combined)