I have invoiced a customer twice for the same period and they have paid both invoices. They want a credit note for the over payment. How do I produce a credit note?

Hello Brian84, 

Thanks for reaching out to us on the Community page, 

The way in which to do a credit note is to, go to the plus icon>credit note> put the customers name in who over page>The amount they over paid and category you want it to be, fill in all the details and then click save and close. The next time you do an invoice for the customer, when you receive payment it will give you the option to click the credit note as well.