Document numbering

Prefix, next number and minimum digits per document type; numbers are issued in sequence and a used number is never handed out twice.

Settings → Numbering.

Each document type — invoice, estimate, credit memo, sales receipt, bill, purchase order, check, and the rest — has its own sequence: a prefix (INV-), the next number to issue, and the minimum digits it is padded to (4 gives INV-1001, INV-1002 …). Change the next number to start from where a previous system left off.

A number is taken when the document is saved, in order; a draft you abandon still keeps its number so an auditor never sees a gap that was silently reused. Typing a number by hand on a document is allowed, and a number that already exists on that type is refused. Voiding keeps the number and the document.