Electronic Tax Liability Register records return and non-return GST liabilities, links positive closing balances to return invalidity and filing prohibition. Form GST PMT-1 establishes an Electronic Tax Liability Register with Part I for return-related liabilities and Part II for non-return liabilities, recording transaction details, debit/credit status, tax-component breakdowns and totals. Part I entries include return liabilities and composition or cancellation-related liabilities and link a positive closing balance to return invalidity and prohibition on filing subsequent returns until discharge. Part II captures non-return demands, payments from ledgers, appeal-based adjustments, refund claims for successful appeals, and status; its closing balance does not affect return filing.