The Commission shall, where appropriate, as soon as possible, present to the Council proposals designed to delimit the scope of the exemptions provided for in Articles 143 and 144 and to lay down the detailed rules for their implementation.

Pending the entry into force of the rules referred to in paragraph 1, Member States may maintain their national provisions in force.

Member States may adapt their national provisions so as to minimise distortion of competition and, in particular, to prevent non-taxation or double taxation within the Community.

Member States may use whatever administrative procedures they consider most appropriate to achieve exemption.

Member States shall notify to the Commission, which shall inform the other Member States accordingly, the provisions of national law which are in force, in so far as these have not already been notified, and those which they adopt pursuant to paragraph 2.