We generally do not pre-invoice based on a provided PO number.  If you are required to go through a purchase order process we recommend the following procedure:

  1. Create a registration for your attendees.
  2. At the end of the process, choose Pay by Check.  This will generate a confirmation/invoice number that can be referenced for your PO.
  3. When issuing payment, please send the corresponding confirmation number along with the payment so that it can be properly applied to your registration. If registering a group, you may use the group registration number generated at the end of your group registration to reference the entire group.