<h1>GSTR-3B interest now offsets minimum Electronic Cash Ledger balance; auto-populated interest is minimum and non-editable downward.</h1> Interest for delayed GSTR-3B filings from January 2026 will be computed on portal as (Net Tax Liability - Minimum Cash Balance in ECL from due date to date of debit) x (Days Delayed/365) x Applicable Interest Rate and auto-populated in Table 5.1 as a non-editable minimum amount; taxpayers must self-assess and increase it if necessary. The portal will auto-populate Tax Liability Breakup from prior-period supply documents, allow CGST/SGST ITC to be used for IGST after IGST ITC is exhausted, and collect interest for late final returns (GSTR-10) of cancelled taxpayers.