GSTR-3B Interest Calculation Now Considers the Minimum Cash Ledger Balance

There has been a useful change in the way the GST portal computes interest in GSTR-3B.

From the January 2026 tax period onwards, GSTN enhanced the calculation in Table 5.1 so that the minimum balance available in the Electronic Cash Ledger during the relevant period is considered in line with the proviso to Rule 88B(1) of the CGST Rules.

In practical terms, this matters where a return is filed late but cash was already lying in the Electronic Cash Ledger.

Earlier, a taxpayer looking only at the delay may have expected interest on the full cash portion of the liability. The revised portal computation takes the relevant minimum cash balance into account while calculating the system-generated amount.

There is one point I would not overlook, though.

The amount shown by the portal should still be reviewed rather than accepted automatically.

GSTN itself states that the auto-populated interest represents the minimum interest required to be paid. The taxpayer is still expected to self-assess the correct liability and increase the amount where necessary.

So if interest appears in Table 5.1, it is worth checking the underlying calculation, particularly:

• the period of delay;
• the tax liability discharged in cash;
• the Electronic Cash Ledger balance during the relevant period; and
• the computation made available by the portal.

The system is doing more of the calculation, but the responsibility for the correct interest liability has not shifted away from the taxpayer.

For businesses with occasional delayed filings, this is a relatively small portal change. For businesses with recurring delays or significant cash balances, it is worth understanding properly rather than treating the auto-populated figure as a black box.

This note reflects the GSTN position checked on 5 September 2026. Where the amount is material or the computation looks unusual, the current portal position and applicable provisions should be reviewed before filing.