Since Ofgem (Ofgem) initially set the RIIO-3 (RIIO-3 Final Determinations) revenue limit in July 2025, capping the allowed TNUoS (Transmission Network Use of System) revenue for 2026-2031, NESO (National Energy System Operator (NESO)) has been publishing draft TNUoS charges for the regulatory year commencing April 2026, the first year of the new price control period.
These same TNUoS charges apply uniformly to meters across the mainland United Kingdom, varying only by meter class. On 30 January 2026, the TNUoS rates for 2026-2027 were published in their finalised form.
While the TNUoS revenue limit was previously around £12 billion during RIIO-2, the new period has a limit of £24.2 billion, representing an increase of more than 80%. Immediately following Ofgem’s announcement, the only indication of the future rates was this percentage increase, applied to the previous rates.
More recently, on 18 September 2025, NESO’s forecast charges averaged 102%, more than double the 2025-2026 average.
TNUoS is one of the larger non-commodity costs included in a typical electricity bill and makes up a fifth of a typical (1 GWh) consumer’s electricity bill, meaning a doubling of TNUoS would translate to a rise of ~20% to end costs, a significant increase to consumers of any scale.
The rises in the final rates from NESO, published 30 January 2026, remain significant, though notably lower than the earlier forecasts Currently, the average increase has fallen to roughly two-thirds, rather than the full doubling of the rates. This represents a percentage rise to an overall bill of ~11%, a gentler rise than the previously anticipated ~20%.
Below is a table comparing NESO’s initial forecasts vs recently published rates for the period April 2026 – March 2027:
| Band Classification | Band | Actual £/Site/Day: April 2025– March 2026 |
09/2025 £/Site/Day: April 2026 – March 2027 |
Actual (01/2026) £/Site/Day: April 2026– March 2027 |
|---|---|---|---|---|
| Low Voltage Non-Half Hourly | 1st band | 0.15 | 0.31 | 0.24 |
| 2nd band | 0.37 | 0.74 | 0.59 | |
| 3rd band | 0.76 | 1.6 | 1.24 | |
| 4th band | 2.07 | 4.41 | 3.46 | |
| Low Voltage Non-Half Hourly – Whole current | 1st band | 0.15 | 0.31 | 0.24 |
| 2nd band | 0.37 | 0.74 | 0.59 | |
| 3rd band | 0.76 | 1.6 | 1.24 | |
| 4th band | 2.07 | 4.41 | 3.46 | |
| Low Voltage Half Hourly - Current Transformer | 1st band | 3.91 | 7.28 | 5.80 |
| 2nd band | 6.53 | 14.41 | 11.51 | |
| 3rd band | 10.25 | 18.01 | 14.38 | |
| 4th band | 22.74 | 48.23 | 38.18 | |
| High Voltage | 1st band | 21.83 | 39.25 | 31.84 |
| 2nd band | 62.8 | 146.54 | 117.15 | |
| 3rd band | 121.8 | 233.35 | 185.42 | |
| 4th band | 317.6 | 667.8 | 528.91 | |
| Extra High Voltage | 1st band | 160.77 | 387.51 | 325.48 |
| 2nd band | 741.79 | 1,394.46 | 1,159.38 | |
| 3rd band | 1,576.23 | 2,897.17 | 2,512.93 | |
| 4th band | 3,882.74 | 6,598.39 | 5,698.39 |
The exact changes in percentage for different meter classes, and the overall average percentage changes, are shown in the table below:
| Band Classification | Unit Measurement | Older % Change | Actual % Change |
|---|---|---|---|
| Low Voltage Non-Half Hourly | Annual Consumption | 106.67 | 59.54 |
| 100.00 | 58.73 | ||
| 110.53 | 63.48 | ||
| 113.04 | 67.20 | ||
| Low Voltage Non-Half Hourly – Whole current | Annual Consumption | 106.67 | 59.54 |
| 100.00 | 58.73 | ||
| 110.53 | 63.48 | ||
| 113.04 | 67.20 | ||
| Low Voltage Half Hourly - Current Transformer | Agreed Supply Capacity | 86.19 | 48.27 |
| 120.67 | 76.29 | ||
| 75.71 | 40.31 | ||
| 112.09 | 67.90 | ||
| High Voltage | Agreed Supply Capacity | 79.80 | 45.85 |
| 133.34 | 86.55 | ||
| 91.58 | 52.23 | ||
| 110.26 | 66.53 | ||
| Extra High Voltage | Agreed Supply Capacity | 141.03 | 102.45 |
| 87.99 | 56.30 | ||
| 83.80 | 59.43 | ||
| 69.94 | 46.76 | ||
| Average Rise | +102.64% | +62.34% | |
This means the largest jump in costs is front-loaded in the 5-year period, with a comparatively softer increase compounding in each following year to make up the 82% bigger revenue limit over the 5 years.
This distribution gives the transmission owners a large sum of their revenue for them to reinvest in the transmission network as soon as possible, beginning work on any projects they may be planning.
An example of such undertakings is the grandly named The Great Grid Upgrade (GGU); while initially begun in April 2023, this series of projects is expected to run until 2030, if not longer. It includes upgrading thousands of kilometres of power lines, further thousands of new underground cables, and other infrastructure investments beyond this. The cost of this overhaul promises to be similarly massive to its scope, with current estimates at over £80 billion by the time of eventual completion.
For moreinformation on the GGU, consider the following article on the topic: TNUoS: The Great Grid Upgrade | NUS Consulting Group.
If you are a client and would like to understand how NUS can support in optimising your non-commodity charges, please contact your Consultant. If you’re an Organisation looking for support and would like to speak to NUS Consulting Group, please contact us.