What is an invoice? The plain definition, with an example

Take away the templates and the software and an invoice is one sentence: I did this work, it costs this much, please pay me by this date, and here's how. Every line on the page exists to make that sentence clear.

That's it. But that one sentence does three jobs at once, which is why invoices have the shape they do.

It gets you paid

Until there's an invoice, finished work is just a favour. The invoice turns it into a specific amount, owed by a specific date. Most clients can't pay you without one: their accounts team needs a document to approve.

It's the record

You both keep it. It's how you know who owes you what, and how your client knows what they spent. That's why each invoice gets its own number: a year from now, someone will be searching for it.

It's what tax is counted from

In a lot of countries, the invoice is the document sales tax or VAT is calculated and claimed from. That's where the stricter rules come from, like your tax number and the tax rate on the page. If you're registered, check what your country requires.

What one looks like

Say you designed a website for a client in Berlin. Your invoice might say: Invoice AB-0114, issued 5 October, due 19 October. Home page design, 18 hours at €95: €1,710. VAT at 23%: €393.30. Total due: €2,103.30. Pay by bank transfer to the account below.

Everything else, like your logo, the layout and the colours, is presentation. Good presentation helps, but that paragraph is the invoice. If you want the full checklist, here are the eight things every invoice needs.

What an invoice isn't

Three documents get confused with it. A quote comes before the work and says what it would cost; nothing is owed yet. A pro forma invoice also comes before, but is laid out like the real invoice, usually so a client can approve the spend or pay a deposit. A receipt comes after payment and proves the money arrived. The last one trips people up most, so it has its own guide.

When to send it

The day you deliver, or on the schedule you agreed, like every two weeks or at each milestone. An invoice that arrives while the work is still fresh gets paid sooner. More on that here.