An invoice records a sale from the seller’s side and asks the buyer to pay for it. At minimum it identifies the two parties, describes the goods or services supplied, states the amount owed with any tax broken out, and gives a unique invoice number, an issue date and payment terms.
An invoice is a request for payment, not proof of it — that is a receipt’s job — and not an order to buy, which is a purchase order. In accounting terms, issuing an invoice is what creates an account receivable for the seller and an account payable for the buyer.
Why It Matters
The invoice is the document the rest of the billing process hangs off: payment terms run from its issue date, bookkeeping entries reference its number, tax authorities treat it as the primary record of the sale, and any dispute starts by comparing it against what was agreed. A complete, correctly numbered invoice is the difference between a payment that can be processed and one that sits in a query queue.
Example
A freelance designer finishes a logo project and issues invoice #2026-014 for $1,200, dated 27 July with terms of Net 14. The client’s bookkeeper records it as a payable, schedules payment for 10 August, and pays referencing the invoice number. The designer marks #2026-014 paid and the books on both sides now tell the same story.
Frequently Asked Questions
Is an invoice the same as a bill?
Same document, different seat at the table. The seller issues an invoice; the buyer receives it as a bill. "Invoice" describes it from the sender’s side, "bill" from the payer’s.
Is an invoice legally binding?
An invoice documents an obligation that already exists from the underlying agreement — it is strong evidence of the debt rather than the contract itself. What an invoice must legally contain varies by country, particularly where VAT or GST applies.