VATREC13010 - Credit and Debit notes: What is the purpose of a credit and debit note?
Credit notes amend or correct previously issued invoices; the invoices are the documents that evidence taxable supplies. The credit note is documentary evidence of a change to that supply, or of a decrease in the consideration for that supply.
Debit notes might be issued where there is an increase in consideration for a supply, rather than a supplementary invoice being raised.
In this guidance only the term ‘credit note’ has been used, although the principles outlined apply equally to debit notes and other documents having the same effect.