Rate of exchange rules revised for valuation under GST; returns, invoice endorsements and input tax credit allocation clarified. Amendments amend exchange rate rules so goods valuation uses the Customs Board notified rate and services valuation follows generally accepted accounting principles for the time of supply. Input tax credit must be determined separately for central, State and integrated taxes. Export invoices must carry specified export endorsements and include recipient, delivery address and country of destination. Where detail-filing deadlines are extended, the Commissioner may require FORM GSTR-3B filing with electronic generation and reconciliation procedures for FORM GSTR-3 and crediting of input tax discrepancies.