An association of eight Central Eastern European transmission system operators (TSOs) which coordinated regional cooperation with regard especially to the mitigation of bottlenecks, CEE TSO was established in April 2007 as a loose association of TSOs with agreed rules of cooperation but without formal legal status. Due to the establishment of Core CCR, the cooperation was formally terminated as of 30 June 2017.

CEE TSO membership consisted of the following TSOs:

  • APG (Austria)
  • ČEPS (Czech Republic)
  • 50Hertz Transmission, TenneT TSO (Germany)
  • PSE (Poland)
  • ELES (Slovenia)
  • MAVIR (Hungary)
  • SEPS (Slovakia)


In addition to operational safety and the coordination of network development, the association  focused its efforts from its very foundation on issues surrounding trade and the coupling of energy markets. The aim of the coordinated allocation of transfer capacity on interconnectors within the CEE region and the implementation of a new FBA (Flow-Based Allocation) allocation methodology drew the main attention of CEE TSO activities. Since March 2012, when national regulatory authorities, together with ACER, agreed on a target model for the coupling of CEE markets based on the so-called Flow-Based Market Coupling, activities concentrated on the preparation of and the putting into practice of the agreed target.

CAO (Central Allocation Office GmbH), a common auction office for 8 CEE TSO members was established in 2008 in Freising near Munich, Germany with the aim of coordinating transfer capacity allocation on interconnectors within the CEE region.

On 1 September 2015,  CAO merged with West European CASC.EU S.A. located in Luxembourg, thus establishing Joint Allocation Office S.A. (JAO). The merger took place after two years of careful and intensive preparation and significant participation of ČEPS who provided office to the project and whose representative was chairing the project team.

Both CAO and CASC.EU run in parallel until the end of 2015 to ensure uninterrupted operation of the monthly and daily auctions on all borders concerned. The transfer of all operations to Luxembourg was concluded by the first quarter of 2016.

The JAO is a joint service company of twenty TSOs from seventeen countries of the Central and Western Europe, which mainly performs the yearly, monthly and daily auctions of transmission rights on 27 borders in Europe and acts as a fall-back for the European Market Coupling.

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