GST Interest Calculator
Section 50, CGST Act — late payment & excess ITC interest
18% applies to delayed payment of tax. 24% applies to undue/excess claim of ITC or excess reduction of output tax liability.
Please fill in the tax amount, due date and payment date to calculate interest.
Interest breakdown
Interest is computed as Tax × Rate × Days ÷ 365, on a simple-interest basis from the day after the due date up to and including the date of payment, per Section 50 of the CGST Act, 2017. This tool is for reference only and does not constitute tax advice — please verify figures with your GST practitioner before filing.
Missing a GST payment deadline doesn’t just mean paying the tax late – it means paying extra. Under Section 50 of the CGST Act, 2017, every taxpayer who delays payment of GST is liable to pay interest on the outstanding amount for each day of delay. Our GST interest calculator lets you work out this amount in seconds, without manually applying the interest formula.
What Is GST Interest and When Does It Apply?
Interest under GST is charged when tax is paid after the due date, or when a taxpayer claims excess Input Tax Credit (ITC) or wrongly reduces output tax liability. Two rates apply:
- 18% per annum – for late payment of GST liability (the standard case for most businesses).
- 24% per annum – for undue or excess claim of ITC, or excess reduction of output tax liability.
Interest is calculated on a simple interest basis, from the day after the due date until the actual date of payment.
How to Use the GST Interest Calculator
Our calculator is designed for quick, error-free results. Here’s how to use it:
- Enter the outstanding tax amount – the GST liability that was paid late or is still pending.
- Select the due date – the date on which the GST payment was originally due (usually the 20th of the following month for most regular taxpayers).
- Select the actual payment date – the date on which the tax was, or will be, actually paid.
- Choose the applicable interest rate – 18% for standard delayed payment, or 24% for excess ITC claims.
- Click “Calculate interest” – the tool instantly shows the number of days delayed, the interest amount, and the total payable (tax plus interest).
The Formula Behind the Calculator
The calculator uses the standard GST interest formula:
Interest = Tax Amount × Rate × Number of Days Delayed ÷ 365
For example, if you delay paying ₹1,00,000 in GST by 30 days at 18% per annum, the interest works out to approximately ₹1,479. Doing this manually for every invoice or return period is tedious and error-prone – the calculator removes that hassle entirely.
Why Use This Tool Before Filing
- Avoid notices and penalties – knowing the exact interest liability helps you pay the correct amount before filing, reducing the chance of a demand notice from the department.
- Plan cash flow – if payment is unavoidably delayed, you can estimate the added cost in advance.
- Save time – no need to manually calculate day counts or apply the formula for every transaction.
A Quick Note
This calculator is a reference tool to help you estimate GST interest liability quickly. Actual interest computed on the GST portal may vary slightly depending on how the department applies day-count conventions and any relevant circulars or notifications in effect at the time of filing. For return filing purposes, always cross-check the figure with your CA or the GST portal before making payment.
