Tax invoice rules: timing, content, exceptions and special documents govern taxable supplies and advance payments. Section 31 requires registered persons to issue a tax invoice for taxable goods at removal or delivery and for taxable services before or within a prescribed period after provision. Invoices must show description, quantity where applicable, value, tax charged and prescribed particulars. Exceptions include prescribed-value supplies, exempt or composition-scheme supplies documented by a bill of supply, revised invoices following registration, receipt and refund vouchers for advance payments, reverse-charge inward-supply invoices and payment vouchers, and special rules for continuous supplies and approval transactions. The term tax invoice includes revised invoices.