 A functionally integrated type III supporting organization ("FISO") performs the operations of the supported organization and remains free the excess business holding excise tax and from the payout rate that shall apply in the near future.A FISO resembles a type III supporting organization that satisfies the "but for" test because they both perform the operations of the supported organization, but the exact requirements for qualifying as a FISO remains unknown.Currently, the IRS has halted determinations on all requests by organizations for FISO classification until the US Treasury Department issues guidance on this matter.