ACER: Eustream's Slovak gas tariff proposal still breaks EU rules on benchmarking and discounts
Victoria Shinder1 min readThe EU energy regulators' agency ACER has published its report on the latest transmission tariff proposal by Eustream, Slovakia's gas transmission system operator. It finds the proposed reference price methodology largely as non-compliant as the version it reviewed in February 2026.
Eustream had first proposed a new methodology for January 2026 to December 2027. In April the Slovak regulator, ÚRSO, approved lower tariffs than Eustream wanted, applied from 1 May 2026. Eustream then consulted again on 30 June with the same tariffs and minor changes. The proposal would introduce a revised method midway through the tariff period, resulting in an increase of more than 50%, which Eustream justifies with a large drop in cross-system flows. It keeps a uniform postage-stamp method, a mix of capacity and commodity charges, and a benchmarking adjustment against other European operators' tariffs.
ACER says the methodology meets the EU requirement on non-discrimination, but compliance on transparency, cost-reflectivity, cross-subsidisation, volume risk and cross-border trade cannot be confirmed, mainly because of the benchmarking adjustment. The commodity charges are non-compliant: the flow-based charge carries a discount for domestic flows that EU rules do not allow.
ÚRSO discontinued the proceeding on 8 October, and a 40-day appeal period is running. ACER says that does not change its obligation to publish. Should the procedure resume, it recommends limiting benchmarking to points with real pipeline competition and phasing out the domestic discount.
What it means
The report keeps the issue alive while the national procedure is formally closed. If Eustream's appeal reopens the case, the regulator now has ACER's list of what would have to change in writing.