The Goods and Services Tax Network (GSTN) has issued an advisory announcing key enhancements in GSTR-3B filing effective from the January 2026 tax period and the auto-populated interest to be non-editable.
The changes primarily relate to interest calculation, auto-population of tax liability break-up, ITC cross-utilisation flexibility, and interest collection in final returns.
The advisory clarifies that these updates are intended to bring the portal’s functionality in line with the proviso to Rule 88B(1) of the CGST Rules, 2017 and Section 50 of the CGST Act, 2017.
Revised Interest Computation Formula in Table 5.1
From the January 2026 tax period onwards, interest computation in Table 5.1 of GSTR-3B has been enhanced to provide taxpayers the benefit of the minimum cash balance available in their Electronic Cash Ledger (ECL) from the due date of return filing until the actual date of tax payment (offset).
Under the revised mechanism, interest will be calculated as:
Interest = (Net Tax Liability – Minimum Cash Balance in ECL from due date to date of debit) × (No. of days delayed / 365) × Applicable Interest Rate
This updated formula ensures that interest is levied only on the net liability after considering the minimum cash balance available during the delay period.
The change will apply to delayed returns filed for the January 2026 tax period. The interest so computed will be auto-populated in the February 2026 GSTR-3B.
System-Computed Interest to Be Non-Editable Downward
The advisory makes it clear that the interest auto-populated in Table 5.1 based on the revised formula will be non-editable downward. Taxpayers will not be allowed to reduce the auto-calculated interest figure on the portal.
However, the GSTN has clarified that the system-computed amount represents only the minimum interest payable. Taxpayers are required to self-assess their actual interest liability and may modify the figure upwards if their records warrant a higher amount.
This move is expected to reduce disputes and bring uniformity in interest computation across taxpayers.
Auto-Population of Tax Liability Breakup Table
Another major enhancement relates to the auto-population of the “Tax Liability Breakup Table” in GSTR-3B.
From January 2026 onwards, the GST portal will auto-populate this table based on the date of documents pertaining to supplies reported in GSTR-1, GSTR-1A, or the Invoice Furnishing Facility (IFF), where such supplies relate to previous tax periods but the tax is being paid in the current period’s GSTR-3B.
This feature is intended to improve transparency in reporting past-period supplies and ensure accurate classification of tax payments.
The breakup can be viewed through the following path:
Login → GSTR-3B Dashboard → Table 6.1 (Payment of Tax) → Tax Liability Breakup
The GSTN has clarified that the auto-populated values are suggestive in nature. Taxpayers may revise them upwards based on their own books and computations.
Suggestive Cross-Utilization of ITC in Table 6.1
In a compliance-friendly update, the GST Portal will now permit greater flexibility in utilisation of input tax credit (ITC).
From January 2026 onwards, once the available IGST ITC is fully exhausted, taxpayers will be allowed to discharge IGST liability using available CGST and SGST ITC in any sequence in Table 6.1 of GSTR-3B.
This enhancement is expected to ease payment planning and reduce procedural rigidities in tax set-off.
Interest Collection in GSTR-10 for Cancelled Taxpayers
The advisory also addresses the issue of delayed filing of the last applicable GSTR-3B by cancelled taxpayers.
In cases where the final GSTR-3B return is filed after the due date, the applicable interest on such delay will be levied and collected through the Final Return, i.e., GSTR-10.
This ensures that interest liability is not bypassed in cases of cancellation and final compliance.
