GST Interest Calculator for GSTR-3B: Formula, Rates and Examples
- Delayed payment of GST generally attracts interest at 18% per annum.
- A 24% rate applies only when ITC is both wrongly availed and utilized.
- From the January 2026 return period, the GST portal considers the minimum eligible balance continuously available in the Electronic Cash Ledger.
- Interest and late fee are separate liabilities and must be paid through the Electronic Cash Ledger.
- Monthly GSTR-3B is normally due on the 20th of the following month, subject to notified extensions.
GST interest is payable when tax is paid after the applicable due date or when wrongly availed input tax credit is actually utilised. However, the calculation is not always based on the full tax liability. The applicable rule, delayed period, Electronic Cash Ledger balance, and the type of liability can all affect the final amount.
This guide explains the GST interest formula, applicable rates, GSTR-3B Table 5.1 calculation, January 2026 portal changes, QRMP rules, and practical examples to help taxpayers verify the amount before filing. It is for accountants, Chartered Accountants, tax professionals, and finance teams responsible for preparing GSTR-3B, checking portal-computed interest, and reconciling GST payments.
What Changed in January 2026?
Table 5.1 of GSTR-3B is used to report interest and late fee relating to previous tax periods. From the January 2026 return period, GSTN enhanced the interest calculation in this table. The portal now considers the minimum eligible balance available in the Electronic Cash Ledger from the return due date until the tax liability is debited while filing the return.
This portal enhancement applies the relief already available under Rule 88B. Notification No. 12/2024-Central Tax provides that an eligible amount deposited on or before the due date may be excluded from the interest calculation if it remains in the Electronic Cash Ledger until it is debited while filing the return.
The system-computed interest is shown in Table 5.1 of the subsequent GSTR-3B. From the January 2026 return period, taxpayers cannot reduce this minimum amount. They may increase it if their own calculation shows that additional interest is payable.
Calculate GST Interest Automatically in GSTR-3B
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How Table 5.1 and the GST Interest Calculator Work
When a GSTR-3B is filed late, the GST portal calculates interest based on the tax liability discharged, the period to which that liability pertains, the filing and debit dates, and the available ledger balance. The resulting amount is generally placed in Table 5.1 of the subsequent GSTR-3B. For a delayed GSTR-3B covered by Rule 88B(1), the system considers:
- The net tax liability paid through the Electronic Cash Ledger
- The normal or extended return due date
- The actual filing and liability-debit date
- The minimum eligible cash balance maintained during the delay
- The applicable interest rate
- The number of delayed days
The detailed tax-head-wise calculation can be checked in the system-generated GSTR-3B PDF.
Tax Liability Breakup
The Tax Liability Breakup identifies supplies from earlier tax periods that are reported and paid through the current GSTR-3B. This helps the portal determine the correct period for which interest must be calculated.
From the January 2026 return period onward, GSTN auto-populates suggested values based on the document dates reported in GSTR-1, GSTR-1A, or IFF. These values should be reconciled with invoices, amendments, debit notes, credit notes , and the books before filing.
The breakup is available through: GSTR-3B Dashboard → Table 6.1 Payment of Tax → Tax Liability Breakup
The suggested values may be revised upward if the taxpayer’s records show a higher liability in an earlier period.
When to Use RE-COMPUTE INTEREST
Use RE-COMPUTE INTEREST if the amount in Table 5.1 does not match the expected ECL benefit or the supporting ledger data.
GSTN reported that, for a few taxpayers, interest for February 2026 appearing in the March 2026 return was calculated without the correct minimum cash-balance benefit. In such cases:
- Click RE-COMPUTE INTEREST.
- Download the updated system-generated GSTR-3B PDF.
- Enter the revised tax-head-wise figures in Table 5.1.
The manually entered amount cannot be lower than the recomputed amount shown in the updated PDF.
Legal Basis and GST Interest Rates
GST interest is governed by Section 50 of the CGST Act and Rule 88B of the CGST Rules. Notification No. 13/2017-Central Tax prescribes interest at 18% for delayed tax payments and 24% where ITC has been wrongly availed and utilised.
| Situation | Interest Rate | Interest Period |
|---|---|---|
| Tax paid after the due date under Section 50(1) | 18% per annum | From the day after the due date until payment. |
| Wrong ITC availed but not utilised | No interest under Section 50(3) | Not applicable. |
| Wrong ITC availed and utilised | 24% per annum | From the date of utilisation until reversal or payment. |
Situation
Interest Rate
Interest Period
Situation
Interest Rate
Interest Period
Situation
Interest Rate
Interest Period
An invoice missing from GSTR-2B does not automatically attract 24% interest. The taxpayer must first check whether the ITC was eligible, wrongly availed, actually utilised, and later reversed or paid.
GST Interest Calculation Formula
Delayed GSTR-3B Covered by Rule 88B(1)
The January 2026 GSTN advisory uses the following portal formula:
Interest = (Net tax liability minus minimum eligible ECL balance) × 18% × number of delayed days ÷ 365
● Net tax liability means the amount payable in cash after eligible ITC .
● Minimum eligible ECL balance means the qualifying balance continuously available from the due date until the date of debit.
● Delayed days begin on the day after the applicable due date and continue through the date the liability is debited when filing the delayed return.
Use this formula only for delayed same-period returns covered by Rule 88B(1). Earlier-period tax liabilities and wrongly utilised ITC are covered by the separate rules below.
Other Unpaid Tax Covered by Rule 88B(2)
Where Rule 88B(1) does not apply, interest is calculated on the tax that remains unpaid from the date on which it was due until the date of payment.
This may include tax for an earlier period that is declared in a later return. The Tax Liability Breakup identifies the period to which the liability belongs.
Wrongly Availed and Utilised ITC
The formula is:
Interest = Wrongly utilised ITC × 24% × utilisation period in days ÷ 365
The utilisation period starts on the date determined under Rule 88B(3), not necessarily the date on which the ITC was first recorded in GSTR-3B.
GST Interest Calculation Examples
Delayed GSTR-3B With ECL Balance
| Particular | Amount or Date |
|---|---|
| Tax liability payable in cash | ₹1,00,000 |
| Normal GSTR-3B due date | 20 March 2026 |
| Return filed and liability debited | 2 April 2026 |
| Delay | 13 days |
| Minimum eligible ECL balance maintained throughout the period | ₹40,000 |
| Interest rate | 18% |
Particular
Amount or Date
Particular
Amount or Date
Particular
Amount or Date
Particular
Amount or Date
Particular
Amount or Date
Particular
Amount or Date
Step 1: Calculate the amount not covered by the ECL balance
₹1,00,000 minus ₹40,000 = ₹60,000
Step 2: Calculate interest
₹60,000 × 18% × 13 ÷ 365 = ₹384.66
The interest is approximately ₹385, subject to the amount displayed and rounded by the system.
Without the qualifying ₹40,000 ECL balance, the calculation would be:
₹1,00,000 × 18% × 13 ÷ 365 = ₹641.10
The qualifying ECL balance reduces the interest by approximately ₹256 in this example.
Note: Do not use only the balance visible on the due date. Download the cash-ledger history and confirm that the qualifying ₹40,000 was not used for another liability before the delayed return was offset.
Wrong ITC Availed but Not Fully Utilised
A taxpayer wrongly avails ITC of ₹80,000.
Situation 1: Credit Was Not Utilised
The Electronic Credit Ledger balance remains at or above ₹80,000 until the entire wrong credit is reversed.
Since the ledger balance never falls below the wrongly availed amount, no part of that credit is treated as utilised for Rule 88B(3) . Section 50(3) interest does not arise merely because the credit was availed.
Situation 2: ₹50,000 of Credit Was Utilised
The ledger balance later falls to ₹30,000.
Wrongly availed ITC: ₹80,000
Remaining credit balance: ₹30,000
Amount treated as utilised: ₹50,000
Interest at 24% is calculated on ₹50,000 from the legally determined utilisation date until reversal or payment. It is not calculated automatically on the full ₹80,000.
Note: This is a simplified illustration. Where wrongly availed IGST credit is involved, the combined balance under the IGST, CGST, and SGST heads must be considered when testing utilisation. Compensation cess credit is not included in that calculation.
GST Interest vs Late Fee
Interest and late fee may apply together, but they are calculated for different reasons.
| Point | Interest | Late Fee |
|---|---|---|
| Trigger | Delayed tax payment or utilisation of wrongly availed ITC | Delayed filing of GSTR-3B |
| Calculation | Percentage calculated for the period of delay | Fixed amount charged for each day of delay. |
| Maximum limit | No general monetary cap | Subject to the applicable late-fee cap. |
| Can both apply together? | Yes | Yes |
Point
Interest
Late Fee
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Interest
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Interest
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Current GSTR-3B Late-Fee Rates
| Return Type | CGST Component | SGST or UTGST Component | Combined Daily Late Fee |
|---|---|---|---|
| GSTR-3B with liability or other than nil return | ₹25 per day | ₹25 per day | ₹50 per day |
| Nil GSTR-3B | ₹10 per day | ₹10 per day | ₹20 per day |
Return Type
CGST Component
SGST or UTGST Component
Combined Daily Late Fee
Return Type
CGST Component
SGST or UTGST Component
Combined Daily Late Fee
Current GSTR-3B Late-Fee Caps
| Return Type | CGST Component | SGST or UTGST Component | Combined Daily Late Fee |
|---|---|---|---|
| GSTR-3B with liability or other than nil return | ₹25 per day | ₹25 per day | ₹50 per day |
| Nil GSTR-3B | ₹10 per day | ₹10 per day | ₹20 per day |
Return Type
CGST Component
SGST or UTGST Component
Combined Daily Late Fee
Return Type
CGST Component
SGST or UTGST Component
Combined Daily Late Fee
These are the combined CGST and SGST or UTGST amounts. A temporary waiver or extension may change the amount for a specified return period, taxpayer class, or affected region.
Interest Rules for QRMP Taxpayers
Eligible taxpayers with aggregate turnover of up to ₹5 crore in the preceding financial year may opt for the QRMP scheme . They file GSTR-3B quarterly but make monthly tax deposits for the first two months through Form GST PMT-06.
The monthly deposit for the first two months is normally due by the 25th of the following month, while the quarterly GSTR-3B is normally due on the 22nd or 24th, depending on the taxpayer’s principal place of business.
Fixed Sum Method
The portal-generated amount is:
- 35% of the cash tax paid in the preceding quarter when the previous GSTR-3B was filed quarterly, or
- 100% of the cash tax paid in the last month of the immediately preceding quarter when the previous returns were monthly.
No interest is charged merely because the actual liability for the month later exceeds the fixed sum, provided:
- The complete system-calculated fixed sum was deposited by the 25th, and
- The entire liability for the quarter is discharged through the quarterly GSTR-3B by its due date.
If the fixed sum is deposited late, interest applies from the PMT-06 due date until payment.
Self-Assessment Method
Under the Self-Assessment Method, the taxpayer calculates the actual monthly net tax after considering eligible ITC . If any part of the monthly net tax remains unpaid after the PMT-06 due date, interest applies from that due date until payment.
How to Check and Pay GST Interest
Step 1: Open the Relevant GSTR-3B
Log in to the GST portal and go to:
Services → Returns → Returns Dashboard → GSTR-3B → Prepare Online
Select the relevant financial year and return period.
Step 2: Review the Interest Liability
Open Table 5.1 and compare the tax-head-wise interest with the latest system-generated GSTR-3B PDF. Confirm that any earlier-period liability has been assigned to the correct period through the Tax Liability Breakup.
Step 3: Create a Challan if Required
If the Electronic Cash Ledger does not contain enough balance, create a challan and deposit the amount under the required tax, interest, and fee heads.
Step 4: Offset the Liability
Use Table 6.1 to offset the complete liability. Interest and late fee must be paid through the Electronic Cash Ledger, as the Electronic Credit Ledger is used only for output tax.
Step 5: File GSTR-3B
After the liability has been offset, file GSTR-3B using DSC or EVC, as applicable.
Records to Keep With the GSTR-3B Working Papers
- The GSTR-1 and GSTR-1A reconciliation
- The purchase register and GSTR-2B reconciliation
- The interest calculation, including delayed days and applicable rate
- The Electronic Cash Ledger extract supporting any ECL relief
- The system-generated GSTR-3B PDF
- Tax-head-wise payment and offset details
These records provide an audit trail for the interest calculation and any ECL relief claimed. BUSY accounting software can help finance teams maintain GST records, reconcile return data, and prepare tax workings before filing on the GST portal.
Conclusion
GST interest calculation is not limited to applying an 18% or 24% rate. The correct amount depends on the tax period, the number of delayed days, the eligible cash balance available in the Electronic Cash Ledger, and whether wrongly availed ITC was actually utilised.
The January 2026 portal update has made the system calculation more reliable, but accountants and finance teams should still verify Table 5.1 against the Electronic Cash Ledger, Tax Liability Breakup, and system-generated GSTR-3B PDF. A documented review before filing can help prevent overpayment, underpayment, and future disputes.
