Rhinoback requires a credit card for single backup accounts that are billed monthly.  For corporate customers who need multiple backup accounts, we can invoice quarterly.  We can also invoice annually for any account.  Professional accounts billed annually receive a 15% discount. 

If you require invoicing please contact us at 404-256-6800 or open a support ticket at: http://www.rhinoback.com/support/Support.aspx?area=3