Receipt voucher requirements prescribe mandatory particulars and default tax treatment when rate or supply nature is indeterminable. Receipt voucher rules require specified particulars: supplier name, address and GSTIN; unique serial number; date; recipient identification; description of goods or services; amount of advance; applicable tax rate and tax amount; place of supply with State and code for inter-State supplies; indication of tax payable on reverse charge basis; and supplier signature. If tax rate is indeterminable, tax is payable at the prescribed default rate; if nature of supply is indeterminable, it is treated as an inter-State supply.