Invoice

An invoice is a time-stamped commercial record that evidences the sale of goods or services between two parties. It names the seller and buyer, itemises what was supplied, shows the amount due, and states the payment terms.

Invoices are the primary document that tax authorities use to verify VAT, GST, or sales tax. Most jurisdictions have specific rules about mandatory content — for example, a unique sequential number, a tax identification number, the supply date, and a VAT breakdown.

The same document can be called different things depending on the market: "invoice" or "bill" in the US and UK, "tax invoice" in Australia and South Africa, "factura" in Spanish-speaking countries, "Rechnung" in Germany, "fattura" in Italy. The underlying legal purpose is the same: a verifiable record of a commercial transaction.