<h1>Interest computation in GSTR-3B updated; portal auto-populates minimum interest and permits CGST/SGST ITC for IGST liabilities.</h1> From January-2026 the portal revises interest computation in GSTR-3B table 5.1 to deduct the minimum cash balance in the Electronic Cash Ledger from net tax liability for interest calculation; the computed interest is auto-populated as a non-editable minimum and taxpayers must self-assess upward if necessary. The portal will auto-populate the Tax Liability Breakup from GSTR-1/GSTR-1A/IFF document dates for prior-period supplies discharged in the current period, and once IGST ITC is exhausted allows use of CGST and SGST ITC in any sequence in Table 6.1. Interest on late final returns for cancelled taxpayers will be collected via GSTR-10.