Article 18 of Regulation No 1/2003 states – without establishing any order of priority between requests -that “[i]n order to carry out the duties assigned to it by this Regulation, the Commission may, by simple request or by decision, require undertakings and associations of undertakings to provide all necessary information”. It is not necessary when sending a request by way of decision for the Commission to have sent a prior simple request for information to the undertaking. The Commission remains nevertheless bound by the principle of proportionality which requires it to have recourse to the least onerous measure when there is a choice between two.

The request for information is sent to the undertaking or association of undertakings concerned. Article 18(4) of Regulation No 1/2003 provides that “the owners of the undertakings or their representatives […] shall supply the information requested on behalf of the undertaking or the association of undertakings concerned”.  The obligation to provide the information requested by the Commission is incumbent on the undertakings or their representatives, or, in the case of legal persons, companies, firms or associations without legal personality, the persons authorized to represent them by law or by their constitution.Information may also be communicated to the Commission by lawyers duly mandated on behalf of their principals, who remain fully responsible for the completeness, accuracy and undistorted nature of the information provided.

The simple request is sent to the undertaking by registered letter with acknowledgment of receipt signed by an official authorized by the Commission. A copy of the letter is also sent simultaneously to the competition authority of the Member State in whose territory the seat of the undertaking or association of undertakings is situated. It must state the legal basis and the purpose of the request, specify what information is required, fix the time-limit within which the information is to be provided and the penalties provided for supplying incorrect or misleading information.

A request for information by way of decision must be notified to the addressee and only takes effect as of notification. A copy of the request must be addressed to the competent authority of the Member State in whose territory the headquarters of the undertaking or association of undertakings is located at the same time as the notification is issued. The request for information must state the legal basis and the purpose of the request, the penalties provided for failure to provide complete and correct information and the remedies available to the undertaking. The formal request for information must, like any Commission decision, state the reasons on which it is based. This is a fundamental requirement: it justifies the request for information and allows the undertakings concerned to assess the scope of the presumed facts that the Commission intends to investigate. The request must indicate those facts with sufficient clarity.

The Commission has sole discretion  to decide whether particular information is necessary. There must, however, be a correlation between the request for information and the presumed infringement and it must not place a disproportionate burden on the undertaking with regard to the needs of investigation.