Created
The invoice has been created and is ready to be sent to the payer. You can Record Payment. The invoice cannot be paid for by the payer.

Billed
The invoice has been approved, and may be scheduled to be sent along with the contract. The invoice can be paid.

Sent
The invoice has been sent to the payer and is waiting to be paid.

Paid
The Invoice has been paid. You can no longer change amounts on the invoice without voiding.

Voided
The Invoice has been voided. The money that was allocated to this invoice can be used on another invoice.

Refunded
The Invoice has been paid, and refunded. The money that was allocated to this invoice can be used on another invoice.