General estimates only. Verify on gst.gov.in & consult CA. Full Disclaimer

Interest calculations on late GST payment trip people up because the rate and the start date both matter, not just the delay. I built this to get both right in one place.

ℹ GST Interest Rules

Under Section 50 of CGST Act, if you pay GST late, you must pay interest at 18% per annum. Interest is calculated from the due date to actual payment date.

Calculate Interest on Delayed GST Payment

Enter the GST amount you paid late (CGST + SGST or IGST)
Leave blank to calculate till today
Default: 18% as per GST law (Section 50 CGST Act)

How Interest is Calculated

1

Interest Rate

GST law mandates 18% per annum interest on delayed payment under Section 50 of CGST Act. This rate applies to CGST, SGST, and IGST.

2

Calculation Period

Interest is calculated from the due date (usually 20th of next month for GSTR-3B) to the actual payment date. Even 1 day delay attracts interest.

3

Formula

Simple Interest: Interest = (Tax Amount Rate Days) / (365 100)

Common Scenarios

Tax Amount Days Late Interest @ 18%
₹10,00010 days₹49
₹50,00030 days₹739
₹1,00,00060 days₹2,959
₹5,00,00090 days₹22,192

When Does GST Interest Apply?

1

Late GSTR-3B Filing

If you file GSTR-3B after the due date (20th of next month for monthly filers), interest at 18% p.a. applies on the net cash tax paid for each day of delay.

2

Wrong ITC Claimed and Utilised

If you claimed excess Input Tax Credit and utilised it, interest at 24% per annum applies under Section 50(3) of CGST Act — higher than the standard 18% rate.

3

Reversal of ITC

When ITC is reversed (e.g., for non-payment to supplier within 180 days, or ineligible ITC), interest at 18% applies from the date of original ITC claim to the date of reversal.

4

Demand and Recovery

If GST is unpaid due to genuine error (Section 73) or fraud (Section 74), interest is part of the demand along with tax and penalty. It continues to accrue until the full amount is deposited.

GST Interest Rate Chart

Situation Interest Rate Section
Late payment of GST (GSTR-3B) 18% per annum Section 50(1) CGST Act
Excess ITC claimed and utilised 24% per annum Section 50(3) CGST Act
ITC reversal (180 days non-payment) 18% per annum Rule 37 CGST Rules
Refund wrongly received 24% per annum Section 54(12) CGST Act

Important Notes

💡 Interest is automatically calculated on GST portal when you file returns
💰 You must pay interest along with delayed tax
📅 Interest applies from due date, not filing date
🔄 For multiple months delay, interest compounds monthly
Interest is NOT tax deductible as business expense

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