Time of supply of goods determines tax liability, usually at invoice issuance or upon receipt of payment. Time of supply of goods is generally the earlier of the date of invoice issuance (or the last date for issuing it) and the date on which payment is received as entered in books or credited to bank. For supplies under reverse charge, time of supply is the earliest of receipt of goods, payment as recorded or debited by the recipient, or the date immediately after a specified period following issue of the supplier's invoice; failing determination, the recipient's books fix the time. Vouchers and indeterminate cases are governed by issue/redemption dates, return filing dates or tax payment dates.