The European Commission has opened formal investigation proceedings concerning Denmark’s proposal to amend its flat-rate tonnage tax scheme for shipping companies. According to this proposal, shipping companies will no longer be required to supply the authorities with financial information relating to transactions with foreign subsidiaries. The Commission is concerned that this could have a negative effect on the possibility of monitoring the scheme for State aid purposes. Such monitoring is considered essential to ensure that these very favourable taxation measures are not extended to activities other than maritime transport. The Commission has invited comments from all interested third parties.