For the purposes of this Section, a taxable person who has a fixed establishment within the territory of the Member State where the tax is due shall be regarded as a taxable person who is not established within that Member State when the following conditions are met:
(a) he makes a taxable supply of goods or of services within the territory of that Member State;
(b) an establishment which the supplier has within the territory of that Member State does not intervene in that supply.