The IOM, officially enquired to the EU to set the definition of private leisure and private business, in accordance to the EU official explanation the use of an aircraft for purpose related to the business of the owner has the right to have the tax free fuel, for this purpose they support the owners with a "Declaration of Commercial Use".
This document is recognized in many places in the UE, in Germany, in UK, in Switzerland... I have been refused in France and Spain, in Italy it depend where you are, in Rome yes, in Olbia yes, in Milan Not...
The document the IOM is providing is translated in all the European languages.
I am flying a M- registered Falcon since 3 yrs.
