FastSpring provides the following information.
Many companies have a VAT that begins with the two letter language ISO 639-1 code where their company is located. FastSpring's VAT number is EU826012240 and it begins with EU because FastSpring is located in the United States, not in a European Union member state.
Verification of VAT EU826012240. Our VAT number cannot be verified by the usual VAT validation services, but would have to be verified by the Mutual Assistance Office (a sub department of the local VAT collection agency) in each EU country from a database available to those offices.
See original announcement: https://support.fastspring.com/entries/62297170