Free GST Interest Calculator Online
Delayed GST payment means interest keeps adding up every day. Calculating it manually with formulas and ECL deductions is confusing. Use this free GST interest calculator to get the exact interest amount in seconds - no formulas, no guesswork.
Selected month due date: 20 April 2026.
Enter CGST, SGST and IGST directly. SGST will match CGST when it is blank.
Minimum cash balance in your Electronic Cash Ledger between due date and filing date. Leave blank (or ₹0) if unknown — interest will be on the full tax amount.
Late Fee (Section 47)
₹0
Interest (Section 50)
₹0.00
Total Penalty
₹0.00
(₹0 − ₹0) × 18% × 0 / 365 = ₹0 × 0.18 × 0 / 365 = ₹0
0 days × ₹50 = ₹0 (CGST: ₹0 + SGST: ₹0)
How to Use the GST Interest Calculator?
Follow these simple steps to calculate your GST interest and late fee in seconds.
Select Return Type and Due Month
Choose GSTR-3B or GSTR-1 from the dropdown. Then pick the tax period month. The calculator will automatically show the correct due date for that return type.
Enter the Actual Filing Date
Enter the date you filed (or plan to file) the return. If the filing date is after the due date, the calculator counts the exact number of days delayed.
Enter Tax Amounts
Enter your CGST, SGST, and IGST liability amounts. If you have a cash balance in your Electronic Cash Ledger (ECL), enter the minimum balance to reduce your interest base as per Rule 88B. For NIL returns, simply tick the NIL Return checkbox.
View Your Results Instantly
The GST interest calculator instantly shows your late fee under Section 47, interest under Section 50, and the total penalty. A detailed formula breakdown shows the exact computation with CGST and SGST split.
Updated as of April 2026
GST Interest and Late Fee Rules You Must Know
This calculator follows the current GST regulations as of April 2026. We will update this page if the Govt. issues new notifications or changes the rates. Here is a clear breakdown of how GST interest and late fees work.
GST Interest - Section 50, CGST Act
Under Section 50 of the CGST Act, interest is charged when you have an outstanding tax liability and you delay paying it. The rate is 18% per annum. It is calculated from the day after the due date to the actual date of payment. Interest does not apply for NIL returns since there is no tax owed.
The result is rounded to the nearest rupee as per standard GST portal behaviour.
Rule 88B - ECL Deduction (Effective January 2026)
Rule 88B allows a deduction from the interest base. If you maintained a minimum cash balance in your Electronic Cash Ledger (ECL) between the due date and the filing date, that amount is excluded from the interest calculation. This means you pay interest only on the genuinely unpaid portion.
If you are unsure of your ECL balance, leave it blank. The calculator defaults to Rs. 0 and computes interest on the full tax amount - the safest, most conservative estimate.
Late Fee - Section 47, CGST Act
A late fee is a fixed daily penalty charged for every day you delay filing, regardless of your tax amount. It always applies to CGST and SGST (never IGST). The rates and caps are as follows.
| Return Type | CGST | SGST | Total/Day | Max Cap |
|---|---|---|---|---|
| Regular Return | Rs. 25/day | Rs. 25/day | Rs. 50/day | Rs. 10,000 |
| NIL Return | Rs. 10/day | Rs. 10/day | Rs. 20/day | Rs. 500 |
IGST is not applicable for late fees. Late fees are levied only under CGST and SGST Acts.
Disclaimer: This calculator reflects GST regulations as of April 2026 including Notification 19/2021-CT, Section 47, Section 50, and Rule 88B of the CGST Act. Zubizi will update this tool if the Govt. issues revised notifications or rate changes. This tool is for informational purposes only. For final liability, consult a qualified CA or GST practitioner.
Why Use Our Free GST Interest Calculator?
Our GST interest calculator uses the exact legal formula from Section 50 of the CGST Act with full Rule 88B ECL deduction support. Get the accurate number instantly.
Legally Accurate Interest Formula
This GST interest calculator uses the correct formula: Interest = (Tax Liability - ECL) x 18% x Days / 365. This follows Section 50 of the CGST Act and the updated Rule 88B (effective January 2026). You get the legally correct number, not an estimate.
Rule 88B ECL Deduction Support
Rule 88B lets you reduce your interest base by the minimum cash balance in your Electronic Cash Ledger during the delay period. Our GST interest calculator is one of the few free tools that supports this deduction. Enter your ECL balance to see accurate interest after the legal deduction.
Works for GSTR-1 and GSTR-3B
GSTR-1 and GSTR-3B have different due dates. GSTR-3B is due on the 20th of the next month. GSTR-1 is due on the 11th. The GST interest calculator automatically picks the correct due date based on your return type. No manual date lookup needed.
NIL Return Handled Correctly
For NIL returns with zero tax liability, interest under Section 50 does not apply. Our GST interest calculator automatically sets interest to Rs. 0 for NIL returns and shows a clear reason. No confusion, no wrong numbers.
Instant Results, No Signup Required
All calculations run directly in your browser. Your tax data is never sent to any server. Results are instant. No account, no OTP, no subscription. This GST interest calculator is 100% free, forever.
Clear Formula Breakdown
It is not enough to see a number. The results panel shows the full interest formula with every component: tax liability, ECL balance, days delayed, rate, and the final rounded amount. This helps you verify the result or explain it to your CA.
Need More Than a Calculator?
Zubizi is built for Indian businesses. Manage billing, inventory, GST returns, and more - all in one place. Try it free.
Frequently Asked Questions
Common questions about the GST interest calculator.
