BSUoS (Balancing Services Use of System)
BSUoS charges pay for the actions the system operator takes to keep electricity supply and demand in balance.
What it is
BSUoS stands for Balancing Services Use of System. It recovers the cost of the actions the national system operator takes to keep electricity supply and demand matched second by second. Since 1 April 2023 these charges have been recovered only from final demand, meaning suppliers and directly connected demand sites, not generators.
Where you will see it
- Folded into your unit rate on a fixed price contract.
- As a separate line on pass-through or flexible contracts.
Why it matters
The system operator, NESO, publishes BSUoS as a fixed tariff in advance. Draft tariffs for April 2027 to March 2028 were published on 21 September 2026, with the final tariffs due in December 2026. A fixed tariff makes the cost easier for suppliers to forecast than the older, variable approach, but it is still passed to customers one way or another.
The question for you is whether your contract fixes it or passes it through. On a non pass-through contract, the supplier takes the risk of changes. Read more in pass-through vs fixed charges.
Example
A small business has a fixed-price contract for 24 months. The supplier's price already includes its estimate of BSUoS, so the bill does not change when the published tariff does. A customer on a pass-through contract would see the change on their bill.
Related terms
TNUoS and DUoS are the other network-related charges. For the bigger picture see non-commodity charges explained.
Common questions on this topic
Sources
General information only. Energy prices, rules and supplier terms change; check the latest position with your supplier, Ofgem or the Energy Ombudsman before you act.