Free GST Interest Calculator
Work out interest on a late GST payment — no signup, nothing sent to a server.
Interest payable
—
Days delayed
—
Total payable (tax + interest)
—
How to calculate GST interest on late payment
-
1
Choose the interest type
Pick "Delayed payment" for late GST paid in cash, or "Excess ITC claimed" for the higher 24% rate.
-
2
Enter the tax amount
Type the GST amount on which interest applies.
-
3
Enter the due date and payment date
The number of days delayed is calculated automatically from the two dates.
-
4
Adjust the rate if needed
The rate defaults to the standard slab for your chosen type, but can be edited for a different scenario.
Example use cases
Filing a delayed GSTR-3B
Work out the interest to add to a GST payment made after the due date.
Reversing excess ITC
Estimate the higher-rate interest applicable when excess input tax credit was claimed and later reversed.
Budgeting for a late filing
Check the total payable — tax plus interest — before making a delayed GST payment.
Frequently asked questions
How is GST interest on late payment calculated?
Interest = tax amount × rate ÷ 100 × (number of days delayed ÷ 365), charged from the day after the due date up to the date of actual payment.
What interest rate applies to delayed GST payment?
Under Section 50 of the CGST Act, delayed payment of GST attracts interest at 18% per annum. Excess Input Tax Credit (ITC) claimed or utilised attracts a higher rate of 24% per annum.
Is interest calculated on the gross tax or only the cash-paid portion?
Interest is generally calculated on the net tax liability paid through the electronic cash ledger, though the exact treatment can depend on how the liability was settled. This calculator uses the tax amount you enter as the base.
Is my GST data sent to a server?
No. The calculation runs entirely in your browser — nothing is transmitted or logged.