GST late fee and interest calculation starts with separating two different defaults: filing a return late and paying tax late. A delayed return can attract a late fee even when no tax is payable. Interest, by contrast, depends on the relevant tax liability and the period for which it remains unpaid.
For CAs, tax consultants and accounts heads, the practical task is to identify the correct due date, applicable late-fee notification and interest-bearing amount before filing.
Statutory content reviewed as of 13 October 2026. Confirm the treatment against the notification in force for the relevant return, tax period and taxpayer category.
Late fee versus interest: the basic distinction
- Late fee under Section 47 of the CGST Act: Applies to delayed furnishing of specified returns or statements. It is generally calculated per day, subject to applicable limits and relief.
- Interest under Section 50 of the CGST Act: Applies to delayed payment of tax and, separately, to input tax credit wrongly availed and utilised.
These charges are not interchangeable. A nil return filed late may attract a late fee without interest. Conversely, delayed payment of a tax liability may attract interest even where the issue is not simply a late-filed return.
Section 47: how GST late fee is calculated
For returns covered by the general daily-fee provision in Section 47, the statutory CGST late fee is ₹100 per day, subject to a maximum of ₹5,000. The corresponding State or Union Territory GST treatment must also be considered.
However, the statutory figure is not necessarily the amount payable. Notifications have reduced daily fees and prescribed different caps for particular returns, periods and categories. Annual returns have a different framework and should not be calculated using routine monthly-return assumptions.
Check the effective rate and cap first
For many GSTR-3B periods, the commonly applicable reduced combined late fee is:
- ₹50 per day for a non-nil return: ₹25 CGST plus ₹25 SGST.
- ₹20 per day for a nil return: ₹10 CGST plus ₹10 SGST.
Do not apply these figures universally. Check the return type, relevant period, nil-return conditions, turnover-linked cap and any special waiver or extension. A return with no cash payment is not automatically a nil return.
The working formula is:
Late fee = Days of delay × Applicable daily fee, subject to the applicable maximum and notification conditions.
Count from the day after the operative due date through the actual filing date. If a valid extension applies, use the extended date. A conditional late-fee waiver is not necessarily a due-date extension.
Section 50: how GST interest is calculated
Interest on delayed payment of tax under Section 50(1) is generally calculated at 18% per annum. It is a time-based charge, not a flat percentage added once to the return liability.
The basic formula is:
Interest = Interest-bearing tax × Annual rate × Days of delay ÷ 365
The key question is which amount belongs in the calculation.
When the cash-paid portion matters
For qualifying supplies declared in a return furnished after its due date, the delayed-return interest framework generally focuses on the tax discharged through the electronic cash ledger rather than the portion discharged using eligible input tax credit.
This is not a universal rule for every unpaid liability. Proceedings-related exceptions, liabilities omitted from earlier returns and other payment situations require separate examination. Rule 88B of the CGST Rules provides the relevant calculation framework.
Also examine amounts already credited to the electronic cash ledger by the due date and remaining available until debit. Specific conditions can affect their exclusion from interest calculation. Do not assume either that every ledger deposit stops interest or that the full cash discharge always attracts it.
Wrongly availed and utilised ITC is different
Section 50(3) addresses input tax credit wrongly availed and utilised, with a notified interest rate of 24% per annum. This needs a utilisation-based examination rather than the ordinary delayed-return calculation.
Do not apply 24% to all late tax payments, or calculate interest merely because an ITC entry was incorrect without checking utilisation and the applicable rules.
Worked example: GSTR-3B filed 10 days late
Assume a regular taxpayer has these facts:
- GSTR-3B due date: 20 January, with no extension.
- Filing and tax discharge date: 30 January.
- Total tax liability: ₹1,00,000.
- Liability discharged using eligible ITC: ₹40,000.
- Liability discharged in cash: ₹60,000.
- Applicable non-nil late fee: ₹50 per day combined.
Assume the cash-based interest treatment applies, no qualifying cash-ledger balance was available by the due date, and no waiver or cap reduces the calculated fee.
Step 1: Count the delay
The period from 21 January to 30 January is 10 days.
Step 2: Calculate the late fee
10 × ₹50 = ₹500
This comprises ₹250 CGST late fee and ₹250 SGST late fee.
Step 3: Calculate interest
₹60,000 × 18% × 10 ÷ 365 = ₹295.89
The illustrative additional cost is therefore ₹795.89 before applicable rounding: ₹500 late fee plus ₹295.89 interest. Allocate interest to the relevant tax heads and verify the final payable figures before discharge.
Checks before finalising the calculation
A reliable working paper should record:
- The return and tax period being filed.
- The operative due date and actual filing date.
- Any extension, waiver, reduced rate or applicable cap.
- The tax payable under each head and eligible ITC available.
- Cash-ledger deposits, debit dates and relevant balances.
- Any earlier-period omissions or wrongly utilised ITC requiring separate calculation.
Do not assume a late-fee waiver also waives interest. Likewise, review portal-generated figures against the underlying facts rather than treating them as a substitute for reconciliation.
Use the free calculator before filing
Use Pinnacle Consultancy Group, Hyderabad’s free GST late fee and interest calculator to prepare an initial estimate. Keep the applicable notification and ledger details alongside the calculation, and verify the final liability before filing.
As a next step, try the free pre-filing simulator to support your pre-filing review. Pinnacle GST360 supports GST analytics and controlled return filing for tax consultants; professional review remains essential.