Designation of Nominated Electricity Market Operators

What is it about?

Each Member State needs to ensure that at least one NEMO is designated to perform the single day-ahead and single intraday coupling. Each NEMO designated in the territory of one Member State has the right to provide its services in other Member States ('passporting').

Member States can refuse the trading services by a NEMO designated in another Member State only in exceptional and specific cases (Article 4(6)). The Member States have also the right to revoke the designation of a NEMO, in case it fails to comply with the criteria set in Article 6 of the CACM Regulation.

Legal basis: Article 4, 5 and 6 of the CACM Regulation

Current status: Access the list of currently designated NEMOs and where they provide services.

Market Coupling Operation plan

What is it about?

The Market Coupling Operation (MCO) plan sets out how all NEMOs jointly establish and perform the market coupling operator functions which include:

• developing and maintaining the algorithms, systems and procedures for single day-ahead and single intraday coupling;
• processing input data on cross-zonal capacity and allocation constraints provided by coordinated capacity calculators;
• operating the price coupling and continuous trading algorithms; and
• validating and sending single day-ahead and intraday coupling results to NEMOs.

The plan also covers the governance principles for performing the market coupling operator functions.

Legal basis: Article 7(3) of the CACM Regulation

Responsibility: all NEMOs

Current status: The MCO Plan was approved by all regulatory authorities in July 2017.  

Implementation: The MCO Plan is implemented once all bidding zone borders in the internal energy market are participating in the single day-ahead coupling and single intraday coupling.

Read more on the latest approved MCO plan.

Documentation on the approval process of this methodology.

Single day-ahead and intraday coupling algorithms

What is it about?

The methodology establishes the requirements for the algorithms used in the day-ahead (price coupling algorithm) and intraday coupling (continuous trading matching algorithm and intraday auction algorithm), along with the criteria to fulfil them. The algorithms need to be scalable, repeatable and aim for maximum economic surplus. The methodology also ensures that any developments enable:

• efficient and timely implementation of the single European electricity market; and
• a close monitoring of the development and operations.

Legal basis: Article 37 of the CACM Regulation

Responsibility: all NEMOs

Current status: The algorithm methodology was approved by ACER in July 2018 and amended in January 2020. Another amendment to include co-optimisation is currently pending ACER’s approval. ACER initially planned to decide on the matter by 24 May 2024, but will now decide by early autumn 2024 to incorporate stakeholders' views on the findings of the related consultancy study.

Update as of 24 September: with its Decision 11-2024, ACER adopted the amended methodology.

Implementation: The methodology has been largely implemented. Implementation of certain functionalities is still pending.

Read more on the latest approved algorithm methodology.

Documentation on the approval process of this methodology.

Single day-ahead and intraday coupling products

What is it about?

The terms and conditions list all products that can be used in the day-ahead and intraday coupling and splits them into two categories: mandatory and optional.

Legal basis: Article 40 (day-ahead) and Article 53 (intraday) of the CACM Regulation

Responsibility: all NEMOs

Current status: The terms and conditions were approved by all regulatory authorities in 2018 and their amendment were approved by ACER in January 2020.

Implementation: The terms and conditions are implemented.

Read more on the latest approved products terms and conditions.

Documentation on the approval process of this methodology.

Minimum and maximum prices

What is it about?

The terms and conditions set out the harmonised maximum and minimum clearing prices to be applied in the market coupling. They are  subject to the application of an automatic adjustment mechanism. This mechanism ensures that an increment to the original maximum price is added if the clearing prices in the day-ahead or intraday coupling nearly reach its maximum limit.

Legal basis: Article 41 (day-ahead) and Article 54 (intraday) of the CACM Regulation

Responsibility: all NEMOs

Current status: The terms and conditions on minimum and maximum prices were approved by ACER in November 2017.

Implementation: The terms and conditions are implemented.

Read more on the latest approved terms and conditions on minimum and maximum prices.

Documentation on the approval process of this methodology.

Back-up methodology

What is it about?

All NEMOs are responsible for establishing, together with the relevant TSOs, the backup procedures for national or regional market operation in case no results are available from the market coupling operation functions.

The methodology ensures a back-up in operating the MCO functions, in case the responsible NEMO is unable to do so. This methodology takes into account the fallback methodology under the CACM Regulation.

Legal basis: Article 36 of the CACM Regulation

Responsibility: all NEMOs (in cooperation with all TSOs)

Current status: The back-up methodology was approved by all regulatory authorities in March 2019. 

Implementation: The methodology is implemented.

Read more on the latest approved back-up methodology.

Documentation on the approval process of this methodology.

Intraday cross-zonal gate opening and closure time

What is it about?

The terms and conditions determine the intraday cross-zonal gate opening (point in time when cross-zonal capacity between bidding zones is released) and closure time (where cross-zonal capacity allocation is no longer permitted).

The intraday cross-zonal gate opening time has been set to 15:00 market time day-ahead.

The intraday cross-zonal gate closure time has been set to 60 minutes before the start of the relevant intraday market time unit on a bidding zone border.

Legal basis: Article 59 of the CACM Regulation

Responsibility: all TSOs

Current status: The terms and conditions were approved by ACER in April 2018.

Implementation: The terms and conditions are implemented in all capacity calculation regions.

On 2 July 2025, TSOs submitted to ACER a proposal to move the gate closure time to 30 minutes before delivery. ACER plans to decide on the matter by 2 January 2026.

Read more on the latest approved terms and conditions for the intraday cross-zonal gate opening and intraday cross-zonal gate closure times.

Documentation on the approval process of this methodology.

Intraday capacity pricing

What is it about?

The pricing mechanism for cross-zonal capacity in the intraday timeframe should be based on intraday auctions. These auctions are part of the single intraday coupling and complement continuous trading, where the available cross-zonal capacity is allocated at a zero price on a first come first serve basis.

The methodology ensures cross-zonal capacity is not allocated to the intraday auctions and the continuous trading at the same time.

Legal basis: Article 55 of the CACM Regulation

Responsibility: all TSOs

Current status: The methodology was approved by ACER in January 2019.

Implementation: The methodology is implemented through the amendments of the algorithm methodology, which introduces intraday auctions as the tool for pricing intraday capacity. The algorithm methodology sets out the implementation of the intraday auctions to the beginning of 2023.

Read more on the latest approved methodology for pricing intraday cross-zonal capacity.

Documentation on the approval process of this methodology.

Day-ahead firmness deadline

What is it about?

The day-ahead firmness deadline methodology defines the deadline after which cross-zonal capacity for the day-ahead allocation becomes firm. The day-ahead firmness deadline is set to 60 minutes before the day-ahead market gate closure time.

Legal basis: Article 69 of the CACM Regulation

Responsibility: all TSOs

Current status: The methodology was approved by all regulatory authorities in July 2017. 

Implementation: The methodology is implemented. 

Read more on the latest approved day-ahead firmness deadline methodology.

Documentation on the approval process of this methodology.

Complementary regional auctions

What is it about?

These provisions allow for the implementation of complementary regional intraday auctions  within or between bidding zones in addition to the single intraday coupling solution if they do not have an adverse impact on the single intraday coupling. TSOs and NEMOs need to establish the methodology to be approved by the relevant regulatory authorities. Their application shall be reviewed at least every two years.

Legal basis: Article 63 of the CACM Regulation

Responsibility: relevant NEMOs and TSOs

Current status: The complementary regional intraday auctions were approved for the bidding zone border between Spain and Portugal and Italy North and Italy-Greece biding zone borders.  

Implementation: The complementary regional intraday auctions are partially implemented (see above).

Read more on the latest approved methodologies for complementary regional intraday auctions.

Documentation on the approval processes of the methodologies for complementary regional intraday auctions.

Fallback procedures

What is it about?

The fallback procedures ensure efficient, transparent and non-discriminatory capacity allocation in case the single day-ahead coupling process is unable to produce results. Different regions have different fallback solutions in place.

Legal basis: Article 44 of the CACM Regulation

Responsibility: all TSOs in each capacity calculation region

Current status: The fallback procedures were approved in all regions. Some regions also approved amendments.

Implementation: The fallback procedures are implemented in all regions.

Read more on the latest approved fallback methodologies of the respective capacity calculation region.

Documentation on the approval processes of the fallback methodologies.

Calculation of scheduled exchanges

What is it about?

Scheduled exchanges are electricity transfers scheduled between geographic areas for each market time unit and for a given direction. The scheduled exchanges between bidding zones, scheduling areas and NEMO trading hubs are calculated by using the net positions and clearing prices of bidding zones (as outputs of the day-ahead and intraday algorithms)

Legal basis: Article 43 (day-ahead) and Article 56 (intraday) of the CACM Regulation

Responsibility: all TSOs

Current status: The methodology for the day-ahead timeframe was approved by all regulatory authorities in March 2019. The methodology for the intraday timeframe was approved by all regulatory authorities in June 2019.

Implementation: The scheduled exchange methodologies are implemented.

Read more on the latest approved scheduled exchange methodologies.

Documentation on the approval process of these methodologies.

Congestion income distribution

What is it about?

The congestion income distribution methodology establishes the rules for collecting and distributing the congestion income on the bidding zone borders within capacity calculation regions from the day-ahead market and for distributing it among the TSOs having interconnectors on that border.

Legal basis: Article 73 of the CACM Regulation

Responsibility: all TSOs

Current status: The latest amendments to the methodology were approved by ACER in 2022.

Implementation: The  implementation is linked to the implementation of the capacity calculation methodology within their respective capacity calculation region, so different regions have different implementation timelines.

Read more on the latest approved congestion income distribution methodology.

Documentation on the approval process of this methodology.

​​​​​​Definition of capacity calculation regions

What is it about?

This methodology groups all the bidding zone borders of the EU's internal energy market into the different capacity calculation regions (CCRs). This is relevant for the functioning of the internal energy market, as it simplifies processes by forming such regional sub-groups. The approach needs to consider for which bidding zone borders the need of coordination is the highest (e.g. taking into account the interdependencies) and where it is most efficient to apply cross regional coordination. Different regional methodologies (such as capacity calculation, redispatching and countertrading) will be applied on the various capacity calculation regions.

Legal basis: Article 15(1) of the CACM Regulation

Responsibility: all Transmission System Operators (TSOs)

Current status: The determination of capacity calculation regions was approved by ACER in March 2024. 

Implementation: The determination of capacity calculation regions is implemented. A future assessment is foreseen to assess the efficiency of the current CCR determination based on information from newly implemented regional methodologies.

Read more on the latest approved determination of capacity calculation regions.

Documentation on the approval process of this methodology.

Check out ENTSO-E’s interactive map of capacity calculation regions. 

Generation and load data provision

What is it about?

The generation and load data provision  methodology sets out requirements related to the delivery of the generation and load data needed to establish the common grid model. It specifies what units and which information need to be submitted to their respective TSOs, as well as their deadlines. 

Legal basis: Article 16 of the CACM Regulation

Responsibility: all TSOs

 Current status: The generation and load data provision methodology was approved by all regulatory authorities in July 2017.

Implementation: The methodology is implemented.

Read more on the latest approved generation and load data provision methodology.

Documentation on the approval process of this methodology.

Common grid model

What is it about?

The common grid model (created by merging all individual grid models of TSOs) provides the best forecast of perspective network states in the relevant market time units used for the day-ahead and intraday capacity calculation.

The methodology defines the rules and procedures for developing and merging the models, including the relevant parameters of network elements, generation and load patterns, net positions of modelled areas and network topology.

Legal basis: Article 17 of the CACM Regulation

Responsibility: all TSOs

Current status: The methodology was approved by all regulatory authorities in May 2017.

Implementation: The implementation deadline foresees the common grid model to become perational and available for the day-ahead and intraday time frames by June 2018. However, implementation is still ongoing.

Read more on the latest approved common grid model methodology for the day-ahead and intraday time frames.

Documentation on the approval process of this methodology.

Capacity calculation methodology

What is it about?

The day-ahead and intraday capacity calculation methodology describes the rules of each capacity calculation region on how to calculate the amount of capacity  available for trading between bidding zones at day-ahead and intraday market time frames. The methodology also complies with the network security standards.

The process

• TSOs define capacity calculation inputs, such as hourly common grid models.

• The inputs  are used by regional coordination centres to calculate the available amount of cross-zonal capacities either by using a flow-based or coordinated Net Transmission Capacity (NTC)  approach, depending on the respective region.

• The final cross-zonal capacities are then made available to the market coupling were they are allocated, enabling trading among bidding zones.

Legal basis: Article 20 of the CACM Regulation

Responsibility: all TSOs in each capacity calculation region

Current status: The methodology was approved in all regions. Some regions also approved amendments, or they are currently under approval.

Implementation: Different regions have different implementation timelines. Some regions have already implemented the methodology, whereas some other are expected to do so by the end of 2022.

Read more on the latest approved capacity calculation methodologies of the respective capacity calculation region.

Documentation on the approval processes of the capacity calculation methodologies of each capacity calculation region.

The development of the CACM Regulation started in 2011 when the Agency developed the Framework Guidelines on Capacity Allocation and Congestion Management  for electricity. These Framework Guidelines were adopted on 29 July 2011.     

Among other elements, the Framework Guidelines included provisions for the forthcoming development of the Network Code on Capacity Allocation and Congestion Management. The core of these requirements was centred around cross-zonal capacity calculation and allocation in the day-ahead and intraday timeframe.

Calculation of capacities between bidding zones should maximise the possibilities to trade between bidding zones taking into account the limitations of existing network infrastructure. Capacity calculation should be efficient, transparent, and strongly coordinated among TSOs. Flow-based capacity calculation should be applied in highly meshed networks, whereas coordinated net transmission capacity (CNTC) calculation may be used in less meshed networks. In the day-ahead timeframe cross-zonal capacity should be allocated via implicit auction (single coupling). For the intraday timeframe cross-zonal capacity should be allocated through implicit continuous allocation (single coupling), which can be complemented with implicit auctions in specific cases.

The Framework Guidelines also define a process to regularly investigate and report on whether existing bidding zones are efficient. In case inefficiencies are identified, the review of bidding zones should be triggered to compare the overall market efficiency of alternative bidding zones configurations against the existing one.

Based on these Framework Guidelines, ENTSO-E was tasked to develop the Network Code on Capacity Allocation and Congestion Management. Subsequently, the draft network code was submitted to the Agency for opinion based on which ENTSO-E revised the network code and resubmitted it to the Agency. Finally, the Agency adopted a recommendation to the European Commission to adopt the Network Code on Capacity Allocation and Congestion Management subject to specific amendments proposed by the Agency. Following this recommendation, the European Commission further revised the network code, which was then finally adopted as a Commission guideline in July 2015 and entered into force in August 2015.

The detailed dates and documents of the above actions are presented below:

Action 1: 29 July 2011: The Agency adopts the Framework Guidelines on Capacity Allocation and Congestion Management for Electricity

Action 2: 27 September 2012: ENTSO-E submits the Network Code on Capacity Allocation and Congestion Management to the Agency

Action 3: 19 December 2012: The Agency adopts the Opinion on the Network Code on Capacity Allocation and Congestion Management

Action 4: 14 March 2013: The Agency adopts the Recommendation on the Network Code on Capacity Allocation and Congestion Management

​Market rules, (or “market codes”) are binding EU rules that couple the national electricity markets and foster their integration into a single European electricity market. The rules promote:

• Market integration

  • Allowing the most efficient use of infrastructure and resources available at European level

  • Creating hedging and new trading opportunities

  • Contributing to the creation of the European internal electricity market

  • Ensuring an adequate level of security of supply

  • Ensuring long-term operation and network development across the European Union

• Fairness and non-discrimination

  • Access to cross-zonal capacity’s access

  • Creating a level playing field among the parties involved

  • Facilitating the participation of demand response and renewable energy sources

• Transparency and reliability of information

• Competition

  • Avoiding market distortions and entry barriers

  • Facilitating the formation of cost-reflective market prices.

The Regulation on the internal market for electricity and the three European Commission regulations on market rules constitute the main legal framework for the European electricity market.

The three regulations are:

1. Forward Capacity Allocation (FCA) Regulation 2016/1719, covering the forward timeframe.

2. Capacity Allocation and Congestion Management (CACM) Regulation 2015/1222, covering the day-ahead and intraday timeframe.

3. Electricity Balancing (EB) Regulation 2017/2195, covering the balancing timeframe.

The regulations envisage the establishment of more detailed rules and procedures, called “terms and conditions or methodologies”, which need to be developed by Transmission System Operators (TSOs) or Nominated Electricity Market Operators (NEMOs) and approved by National Regulatory Authorities (NRAs) or ACER.

Read more on the different market rules for the various electricity market timeframes.

​​​​​​The network code on the requirements for generators (RfG Regulation​) establishes a set of harmonised rules for generators to connect to the grid, namely synchronous power-generating modules, power park modules and offshore power park modules. The RfG Regulation entered into force on 17 May 2016. ​

​​​​​The High Voltage Direct Current Connections Network Code (HVDC Regulation) establishes the requirements for the connection of HVDC systems and direct current-connected power park modules. The Regulation entered into force on 28 September 2016. ​

​​​​​​The Demand Connection Network Code (DCC Regulation) sets harmonised standards for connecting large renewable energy production plants and integrate demand response. The Regulation entered into force on 7 September 2016. ​