ACER adopts third amendment to mFRR Implementation Framework, harmonising EU-wide FRR prequalification and BSP terms and conditions

On 18 September 2026 ACER adopted Decision No 13/2026 approving the third amendment to the mFRR Implementation Framework (mFRRIF) submitted by all TSOs via ENTSO-E on 18 December 2025. The amendment introduces a Common Harmonisation Proposal (CHP) establishing harmonised terms and conditions for Balancing Service Providers (BSPs), centred on the FRR prequalification process for Reserve Providing Units (RPUs) and Reserve Providing Groups (RPGs). ACER placed three prequalification approaches (activation test, ex-post verification, and an optional fast-track approach) on equal legal footing, amended timelines for application completeness and technical evaluation to align with Article 159 of the SO Regulation, and revised provisions on switching of RPUs between BSPs, re-prequalification, termination of prequalification, and data exchange standards, following extensive consultation with all TSOs, the Belgian regulatory authority, ACER's Electricity Working Group, and a public consultation.

This decision reshapes how balancing service providers across the EU qualify to sell manual Frequency Restoration Reserve (mFRR) balancing energy, directly affecting market entry costs and timelines for new and small providers while TSOs retain tools to safeguard system security. By equalising activation-test, ex-post verification and fast-track routes, ACER aims to lower barriers to entry into balancing markets and support the growing participation of small controllable units, aggregators and flexibility providers, while preserving TSOs' ability to impose proportionate safeguards through national terms and conditions.

The Decision operationalises the EU Balancing Guideline's harmonisation mandate (Article 20(3)(f) EB Regulation) for BSP terms and conditions, converting previously TSO-proposed, nationally fragmented prequalification practices into a common EU-wide framework subject to ACER oversight. The core design tension resolved here is between market-access facilitation (favouring ex-post verification and fast-track routes for small assets) and system security (favouring TSO discretion, activation testing, and volume limits on ex-post verification, especially for large RPGs). ACER's decision to place all three prequalification approaches on 'equal footing' rather than retaining activation testing as the mandatory default is the most consequential design choice, potentially accelerating market entry for aggregated small-scale flexibility resources across the EU balancing platforms (MARI/PICASSO-adjacent mFRR exchange). However, implementation remains contingent on subsequent national terms and conditions for BSPs, to be developed by each TSO and approved by national regulatory authorities—meaning the practical, harmonised effect on cross-border balancing market functioning will only materialise progressively as each Member State transposes the CHP. The dispute over 'penalties' vs 'incentives' terminology in the fast-track clause, and disagreements over discretionary TSO powers versus national terms and conditions, illustrate the ongoing negotiation between centralised EU harmonisation and preserved national/TSO flexibility—an unresolved tension likely to recur in future mFRRIF survey cycles.

Commission Regulation (EU) 2017/2195 (EB Regulation), Article 20 and 21; Commission Regulation (EU) 2017/1485 (SO Regulation), Articles 158, 159, 182; Regulation (EU) 2019/942, Article 5(2)(b); mFRR Implementation Framework (mFRRIF) Article 20

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