Receipt voucher requirements: specify supplier and recipient details, tax particulars, and fallback rules for indeterminate rate or supply nature. Receipt vouchers must list supplier and recipient identification (including GSTIN/UIN), a unique serial number for the financial year, issue date, goods or services description, advance amount, applicable tax rates and tax amounts for each tax head, place of supply with State details for inter State transactions, reverse charge indication, and supplier signature. If the tax rate is indeterminable at receipt of advance, tax is payable at the prescribed fallback rate; if the nature of supply is indeterminable, it is treated as an inter State supply.