An Advisory Committee on Concentrations between undertakings must be consulted before any final decision is taken or before a fine is imposed, with the exception of provisional decisions taken pursuant to Article 18(2) (Regulation No 139/2004, Art. 19). The Advisory Committee is composed of representatives of the competent authorities of the Member States, who designate one or two representatives who may be replaced by another if they are unable to attend. At least one of these representatives must be competent in the field of restrictive practices and dominant positions. On invitation by the Commission, to which a statement of the case is annexed with an explanation of the documents for each case to be examined, the consultation takes place during a joint meeting, which must be held at the earliest ten working days after the invitation has been sent. This time-limit may exceptionally be shortened in order to avoid serious harm to one or more of the undertakings concerned by a concentration ( Regulation No 139/2004, Art. 19). Failure to comply with the time-limit for convening the Advisory Committee does not affect the legality of the final decision, as long as the Committee has had sufficient time to issue its opinion in full knowledge of the facts, even in the absence of exceptional circumstances.

The Committee issues an opinion which is communicated to the addressees of the decision. The Commission may make the opinion public together with the decision, having regard to the legitimate interest of undertakings in the protection of their business secrets. The Commission is not bound by the opinion but must nevertheless give it its utmost consideration.