What is a pro forma invoice and when do you need one

A pro forma invoice looks almost identical to a regular invoice, but it isn't a request for payment yet, it's a preview.

What it's for

A pro forma invoice is sent before work begins or before goods ship, to give the client a clear preview of what they'll be charged. It's commonly used for international shipments (customs often require one), large projects where a client's internal approval process needs to see costs before committing, or new client relationships where both sides want cost clarity locked in before work starts.

How it differs from a standard invoice

A pro forma invoice isn't legally a demand for payment and typically isn't entered into accounting records as a receivable, since the transaction hasn't been finalised. Once the client confirms and the work is delivered, you issue a standard invoice, usually with the same invoice number sequence, referencing that it follows the pro forma.

Labelling matters

Mark it clearly as "Pro Forma Invoice" in the document title, not just "Invoice." Sending an unlabelled pro forma risks a client's accounts payable system treating it as a real invoice and either paying early against work that hasn't happened, or flagging it as a duplicate when the real invoice arrives later.