The short answer
An invoice is a document a business or freelancer sends to a customer after delivering goods or services. It lists what was provided, how much it costs, and when payment is due. Sending an invoice is how you ask to get paid — professionally and on the record.
What every invoice must include
There is no universal legal template, but a complete invoice typically contains:
- Invoice number— a unique reference for your records and the client's accounts.
- Invoice date — the date you issued the document.
- Your business name and address — or your personal details if you are self-employed.
- Client name and address — the person or company you are billing.
- Line items — a description of each product or service, quantity, unit price, and subtotal.
- Total amount due — including any taxes, discounts, or shipping.
- Payment terms — when payment is due (e.g. Net 30) and accepted payment methods.
Invoice vs. quote vs. receipt
A quote is sent before work begins and estimates the cost. An invoice is sent after the work and requests payment. A receipt is issued once payment has been made and confirms the transaction is closed.
When should you send an invoice?
Send an invoice as soon as you deliver the work or product. Delaying the invoice delays your payment. For ongoing projects, you might invoice at pre-agreed milestones or on a monthly schedule.
Do invoices have legal weight?
Yes. An invoice is a legally binding document that can be used as evidence in a payment dispute. Courts and tax authorities treat invoices as proof of a commercial transaction. That is why accurate, consistent invoicing is so important.