Recurring invoices are useful when you have recurring type of work for which you charge your client on a weekly, monthly, or yearly basis. It works great for retainer projects where the amount is the same each time.
To create a recurring invoice, go to Accounting → Recurring → Create a recurring profile by selecting the start date, frequency, occurrences, if you wish them to be sent automatically or not and to attach a PDF to the email.
When the start date comes, they will be created and appear in the Invoices area.
NOTE: If you don't select the Send Automatically option, you will need to go to the desired invoice and send it manually by clicking on the Send button.