Rate of exchange for valuation clarified and input tax credit allocation plus modified return procedures provided under amended GST rules. The amendments align the rate of exchange for valuation: Customs Board rates apply for goods and generally accepted accounting principles apply for services; input tax credit is to be determined separately by tax type and where invoices are unavailable may be estimated at prevailing market price; electronic procedures permit FORM GSTR-3B to be used for interim filing with electronic generation and reconciliation of FORM GSTR-3 parts and crediting of excess input tax to the electronic credit ledger.