Latest EU directives which regulate the traction energy metering and billing are:

Commission Regulation (EU) No 1301/2014 of 18 November 2014 on the technical specifications for interoperability relating to the ‘energy’ subsystem of the rail system in the Union (link to EU portal)

Commission Regulation (EU) No 1302/2014 of 18 November 2014 concerning a technical specification for interoperability relating to the ‘rolling stock — locomotives and passenger rolling stock’ subsystem of the rail system in the European Union (link to EU portal)

Commission Implementing Regulation (EU) No 869/2014 of 11 August 2014 on new rail passenger services (link to EU portal)