Invoicing glossary

Short, plain-language definitions of the terms you meet when you invoice. General information, not legal or tax advice.

Invoicing has its own vocabulary, and getting a term wrong on a real document can cost you time or money, for example sending a proforma invoice when a client's accounts team needed a commercial one. Each entry below gives a short definition, how the term differs from the ones it is commonly confused with, and a link to the tool that produces that document, so you can go from definition to a finished PDF in a couple of clicks.

C

Credit note
A document a seller issues to reduce or cancel part or all of an invoice already sent, for a return, a correction or a discount.

P

Pro forma invoice
A preliminary document that states what you will charge before the work is done or the goods are shipped. It can be used to request an advance payment, but it is not the final invoice or a tax record.
Purchase order
A document a buyer sends to a seller to order goods or services at agreed prices. The PO number is then quoted on the seller's invoice.