When you pay for electricity, you are paying for two fundamentally different things: the electricity itself, and the infrastructure that delivers it to your building. Transportation charges cover the second category and typically represent 25 to 35% of a business electricity bill.
DUoS charges are levied by your local Distribution Network Operator, the company responsible for the cables, transformers and switching equipment between the high voltage transmission network and your premises. There are 14 electricity distribution licence areas across Great Britain, operated by 6 DNO groups, each with their own approved charge structure.
TNUoS charges are levied by the National Energy System Operator (NESO) to recover the costs of building, operating and maintaining the UK's high voltage electricity transmission network. These charges are set annually, take effect each April, and apply to all electricity consumers through their supplier.
The average year on year increase in the residual charge is approximately 63%, rising from £15.72/MWh in 2025/26 to £25.68/MWh in 2026/27, under the new RIIO-3 price control period. The rise is driven by significant grid investment required to support the UK's clean energy ambitions. Costs are expected to continue rising over the next five years. Charges are recovered through two main elements. The first is a fixed standing charge based on your meter type and capacity, which cannot be reduced through energy management. The second is a regional volumetric charge, which for larger Half Hourly metered sites in southern GB retains a link to peak winter demand periods. Understanding how these charges apply to your site is increasingly important as TNUoS becomes a larger proportion of your overall electricity bill.
BSUoS covers the cost of keeping the grid balanced in real time, the continuous process of matching supply to demand at every moment. BSUoS has been charged as a fixed volumetric tariff set in advance since April 2023 and is passed through at cost on pass through and flexible contracts. The current risk for bill payers is not in period volatility but under recovery against the fixed tariff feeding into higher future tariffs.
DUoS misapplication is one of the most common billing errors we encounter. If your profile class has been incorrectly categorised, you may be paying the wrong DUoS rate. Historical audits can identify this and recover the overcharge retrospectively.