A draft release from the National Energy System Operator (NESO) outlines substantial increases in the Transmission Network Use of System (TNUoS) charges for the 2026–27 period, pointing to a notable jump from current 2025–26 levels.
These charges help cover the upkeep and development of the UK’s transmission network—the high-voltage infrastructure that transports electricity nationwide. TNUoS fees fall into two main categories:
- Residual charges: fixed amounts shared among users
- Locational charges: rates that vary depending on where electricity is consumed or generated
Projected Customer Impact
According to NESO’s forecast, a standard user classed as Low Voltage Site Specific Residual Band 2 (LVSS RB2) could face a 38% increase in total TNUoS charges in 2026–27. Regional variations mean the impact will differ across the UK:
- Lowest rise: London, with a 35% increase
- Highest rise: South West, at 40%
What’s Behind the Surge?
A large part of the increase stems from a projected £1.01 billion rise in revenue recovery through demand-related charges. This higher requirement is linked to:
- Anticipated growth in the costs from onshore and offshore transmission network operators
- Increased contributions from interconnectors (which link the UK grid to international systems)
These are early-stage estimates, not confirmed figures. Final revenue allowances will be settled in Winter 2025. For now, the projections rely on assumptions, including adjustments of the 2025–26 data—such as inflating National Grid Electricity Transmission (NGET) values.
Of the £1.01bn uplift, around £997 million (nearly 99%) is expected to be collected via residual charges—highlighting why this element is the primary driver of the forecasted cost increase. Depending on the user group, residual charges could go up by 5% to 49%.
Locational Charge Adjustments
Locational components of the TNUoS charge are also expected to rise, although they represent a smaller share of total costs. The national average increase for this part is estimated at 16%, but again, the effect varies by region:
- South West: a 54% rise, largely due to reduced local generation and more imported electricity
- East of England: a 43% drop, thanks to updated demand and generation modelling
Because these charges depend on real-time power flows and network patterns, they are subject to greater volatility and can shift substantially year to year.
Comparing with Previous Forecasts
NESO’s earlier Five-Year View (published in April 2024) suggested a smaller jump in charges than currently projected. The draft for 2026–27 is now expected to be 25% higher than those initial forecasts, with residual charges making up the bulk of the difference.
Locational forecasts have also changed significantly:
- Midlands: +214%
- South Wales: +298%
- East: –73%
Looking Ahead
An updated Five-Year View is due in August 2025, which may revise these forecasts further. Finalised TNUoS tariffs for 2026–27 will follow the outcome of the price control process in late 2025.
Until then, all numbers remain provisional, and customer impacts could change as more accurate cost data becomes available.
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