Kiwibill specifies the following statuses for your Invoices:
Draft
This is the first status that your Invoice will get. In sequential numbering, the invoice will not be assigned a number until the status changes to Send. There is no limitation to the number of Drafts you can create. Drafts will show up in the Reports, and all calculations will take them into consideration and group them under Drafts.
Sent
An invoice will change it's status to Send, when you either Send your invoice to your Client, or manually Mark it as Sent.
Once an invoice is Marked as Sent, you can add Payments to this Invoice. Payments are not available for Invoices that are still in Draft status.
PartPaid
An invoice will change to Partially Paid status, once a Payment has been added to the invoice, but the sum is not enough to cover the invoice total.
Paid
Once a Payment has been added that covers the total amount of the invoice, the status of the Invoice will change to Paid.