The appointment of the President of the European Commission and of the Commissioners takes place in line with Article 17(7) of the Treaty on the European Union (TEU). The European Commission as an institution is responsible for ensuring the smooth transition between the current and the next Members of the College of Commissioners. In line with standard practice, the European Commission has adopted a set of rules specifying the practical arrangements for the candidate for President/President-elect and the Commissioners-designate in the months preceding their appointment to the new Commission.
These arrangements mirror the ones put in place back in 2014, when the Juncker Commission was preparing to take office. They take into account the fact that both the candidate for President/ President-elect and Commissioners-designate need to spend considerable time in Brussels, Luxembourg and/or Strasbourg while preparing to officially take up their duties.
More concretely, following their nomination, the candidate for President/President-elect would be entitled to an office in the Commission premises, the necessary IT equipment, as well as to a limited number of staff members to support his or her work. The same would be provided to the Commissioners-designate as of the moment that the President-elect announces that he or she has accepted them as candidates for Member of the Commission.
Both the candidate for President/President-elect and the Commissioners-designate would also be able to rely on the support of the Commission services, including the Commission representations in the EU Member States, in relation to their possible travels. The full text of the rules is available online here.