What Are TNUoS Charges?
Transmission Network Use of System (TNUoS) charges cover the cost of running and upgrading the UK’s high-voltage electricity transmission network. They ensure power can move efficiently from generation sites -such as offshore wind farms – to homes and businesses nationwide.
These charges are applied to energy suppliers and passed through to end users via the standing charge on your bill. And from April 2026, those standing charges are set to climb steeply.
What’s Changing in April 2026?
The National Energy System Operator (NESO) has forecast a dramatic increase in TNUoS tariffs for the 2026/27 financial year.
- TNUoS residual pot (TDR): rising from £3.84bn in 2025/26 to £7.52bn in 2026/27
- Increase: around 94% year-on-year
- Reason: large-scale grid upgrades to support the UK’s renewable transition
This means your daily standing charge -the fixed part of your bill – will increase substantially, regardless of how much energy you use.
📊 Forecasted Standing Charge Increases
| Meter Type |
2025/26 TDR (£/day) |
2026/27 TDR (£/day) |
Daily Increase |
Approx. Annual Impact |
| Small Business (NHH Medium) |
£0.76 |
£1.60 |
+£0.84 |
~£306 |
| HH LV1 (0–80 kVA) |
£3.91 |
£7.28 |
+£3.37 |
~£1,230 |
| HH LV2 (80–500 kVA) |
£6.53 |
£14.41 |
+£7.88 |
~£2,876 |
*These figures isolate the TNUoS portion of the standing charge. Actual impact may vary by region and meter band.*
🌍 Why Are TNUoS Charges Increasing?
The main reason is investment in the grid. As more renewable generation connects to the network – often in remote parts of the UK – major reinforcements are required to carry electricity to demand centres in the South and Midlands.
This next phase of investment falls under Ofgem’s RIIO-3 price control framework (2026–2031), designed to make the grid reliable, flexible and net-zero ready.
While this is a positive move for the long-term sustainability of the UK’s energy system, it comes with short-term cost pressure for businesses.
📍 Regional Differences
Not all areas will feel the impact equally.
Businesses in South Wales, South West England, and South East England are forecast to experience the highest increases in standing charges due to network demand and regional pricing structures.
🔒 Fixed vs Pass-Through Contracts – Are You Protected?
Many businesses assume that a fixed-term energy contract locks in every cost – but TNUoS is often excluded.
Most suppliers treat TNUoS as a pass-through charge, meaning it can still increase mid-contract.
Supplier Examples:
| Supplier |
TNUoS Treatment |
Can Change Mid-Contract? |
| British Gas |
Pass-through |
✅ Yes |
| EDF |
Fixed or pass-through (varies) |
✅ Yes (if pass-through) |
| SSE |
Pass-through (quarterly updates) |
✅ Yes |
| ScottishPower |
Pass-through |
✅ Yes |
| Valda Energy |
Non-commodity cost (pass-through) |
✅ Yes |
*Based on supplier T&Cs as of 2025 — always check your own contract pack for confirmation.*
Key Phrases to Check in Your Contract
If your contract runs beyond April 2026, check your terms and conditions for these key phrases:
- “Pass-through costs”
- “Non-commodity costs”
- “Use of system charges”
- “Industry/regulated cost adjustments”
If these appear, your standing charge will likely rise in line with the new TNUoS tariffs.
🗓️ Key Dates to Watch
| Date |
Event |
Notes |
| 30 Nov 2025 |
Draft 2026/27 TNUoS Tariffs |
NESO publishes draft tariffs showing expected standing charge increases for each meter band. |
| 31 Jan 2026 |
Final 2026/27 TNUoS Tariffs |
Final tariffs are locked in — update your budgets to reflect confirmed standing charges. |
| 1 Apr 2026 |
Go-Live Date |
New TNUoS tariffs take effect. Standing charges increase if TNUoS is pass-through. |
*Use these key dates to plan ahead for contract renewals, budgeting, and tariff management.*
💡 What Businesses Should Do Now
- 1. Review Your Contract – Check whether your supplier lists TNUoS as pass-through. If it does, expect a standing charge rise from April 2026.
- 2. Plan Your Renewal Dates – If possible, align your contract term to end before the new tariffs take effect. That way, you can secure a fully fixed deal that includes the 2026/27 TNUoS rates.
- 3. Update Budgets Early – Build these forecasts into your 2026/27 budgets now. A typical SME could see £300–£3,000+ per year added to standing charges.
- 4. Explore On-Site Renewables – Installing solar PV or battery storage can help reduce grid dependency, cut your peak demand, and offset rising costs over time.
- 5. Compare Energy Rates – A competitive unit rate can help balance out standing charge increases. Even a 0.5p/kWh saving on 150,000 kWh/year could save £750 annually, offsetting most of the new TNUoS impact.
📊 Why Unit Rates Still Matter
While standing charges are increasing, your unit rate (p/kWh) still makes up the majority of your overall bill. A low standing charge can easily be cancelled out by a higher unit rate, so always consider both when renewing.
🧭 Final Thoughts
The 2026 TNUoS changes represent one of the biggest shifts in business energy costs for years.
They’re not caused by suppliers – they’re a national adjustment to fund a cleaner, more reliable grid. But for businesses, the effect will be felt directly through higher standing charges.
The best way to stay ahead is to prepare early.
Review your contract, understand your terms, and speak to an energy expert who can help you secure the best possible rates before April 2026.
⚡ Get Ahead of the 2026 Tariff Increase
At WeSave, we help businesses across the UK compare quotes from over 28 energy suppliers – so you can lock in competitive rates before new charges take effect.
Get a free comparison today and find out how much you could save.