GST payment obligations require electronic remittance and ledger sequencing to validate returns and permit input tax credit. GST payment obligations require suppliers to pay CGST/SGST for intra state supplies and IGST for inter state supplies; certain persons face TDS or TCS. Payments are electronic via the Common Portal using CPIN/CIN, with Cash and ITC e ledgers and a tax liability register. ITC may be used only for tax, cash ledger for other amounts; returns without full self assessed tax are not valid. Sequencing rules dictate application of payments to prior periods before current liabilities.