Xero: How Documents Post
A bill
A supplier emails an invoice. This is everything between that email and a draft bill in Xero.
A receipt
A receipt is not a bill: nothing is owed, the money already moved. The question is which transaction already in your books it belongs to.
A credit memo
A supplier credits you for a return or an overcharge. Nothing is owed and nothing is scheduled — it is coded and posted the same way a bill is.
