If you need to write off a debt, realized you have made a mistake or you are wanting to create a shortfall (for our insurance based customers) then credit notes are the way to go.
Credit notes are a great way to balance your books.
1. First find the client you wish to create the credit note for:
2. Then click the 'Financials' tab, select Edit on the invoice you wish to credit note
3. Now select Invoice > Credit Note
4. Now select Invoice > Credit Note. Here you can give a 'Type Reason', which allows you to report on reasons for creating credit notes.