GSTR-3B Late Fee & Interest Calculator (2026 Guide)

What is GSTR-3B and Its Due Date?

GSTR-3B is a monthly self-declaration return that summarizes your outward supplies, input tax credit (ITC), and tax liability.

GSTR 3B Due Date (2026)

• Monthly Filers: 20th of the following month

• QRMP Scheme (Quarterly Filers):

               22nd of the following month (for some states)

               24th of the following month (for other states)

Missing the GSTR 3B due date triggers penalties in the form of interest and late fees.

What Happens If You Miss the GSTR-3B Due Date?

If you fail to file on time, you may face:

• Interest on outstanding tax liability

• Late fees per day of delay

• Restriction on filing future returns

• Loss of compliance rating

GSTR-3B Interest Calculation (2026)

Interest is charged under GST when tax is not paid on time.

Interest Rate:

18% per annum on unpaid tax

Formula to Calculate Interest:

Interest = (Tax Amount × 18% × Number of Days Delay) ÷ 365

Example:

Tax payable: ₹50,000

Delay: 10 days

Interest = (50,000 × 18% × 10) ÷ 365 = ₹246 (approx.)

GSTR-3B Late Fee Calculation

Late fees are charged for delayed filing even if there is no tax liability.

Late Fee Structure:

₹50 per day (split equally as ₹25 CGST and ₹25 SGST)

₹20 per day (Nil return)

Maximum: ₹10,000

Example:

Delay: 10 days

Late fee = ₹50 × 10 = ₹500

GSTR-3B Interest & Late Fee Calculator (How to Use)

To simplify calculations, follow these steps:

• Enter your total tax liability

• Input the number of delayed days

• Apply the interest formula (18%)

• Calculate late fee based on delay

• Add both values for total penalty

Using a calculator helps avoid manual errors and ensures accurate compliance.

Tips to Avoid GSTR-3B Penalties

• Track the GSTR 3B due date every month

• Set reminders before deadlines

• Maintain accurate accounting records

• Reconcile ITC regularly

• File returns even if there is no transaction (Nil return)

Related Insight: Income Tax Return Filing in India

While managing GST compliance, businesses should also stay updated with filing income tax returns in India.

Key Points:

• The last date for filing income tax return in India is generally 31st July (for individuals)

• Timely filing helps avoid penalties and legal notices

• There are several benefits of filing income tax return in India, such as:

• Easy loan approvals

• Proof of income

• Faster visa processing

• Avoidance of penalties

Managing both GST and income tax efficiently ensures overall financial discipline.

Conclusion

Understanding how to calculate GSTR-3B interest and late fees is crucial for avoiding unnecessary financial losses. Keeping track of the GSTR 3B due date and maintaining proper compliance can save your business from penalties and stress.

At Sri Balaji Tax Services, we go beyond just compliance—we provide end-to-end support for GST filing, income tax returns, and financial planning. Our expert team ensures that your returns are filed accurately and on time, helping you focus on growing your business without worrying about deadlines or penalties.

FAQs on GSTR-3B Interest & Late Fees

1. What is the GSTR 3B due date for monthly filers?
The due date is the 20th of the following month.

2. Is late fee applicable if there is no tax liability?
Yes, a reduced late fee of ₹20 per day is applicable for Nil returns.

3. Can I file GSTR-3B after the due date?
Yes, but you must pay applicable interest and late fees.

4. How is interest calculated on delayed GST payment?
Interest is calculated at 18% per annum on the outstanding tax amount.

5. What is the maximum late fee for GSTR-3B?
The maximum late fee is capped at ₹10,000.