On 1 April 2026, TNUoS charges rose by up to 60% on average across GB businesses with some individual bands seeing increases of over 100%. For many commercial sites, the result was thousands of pounds per year in additional standing charges.
Below, find out what changed, what this means to your business, and what you can do about it.
What changed from April 2026
NESO (the National Energy System Operator) sets TNUoS tariffs, and published draft TNUoS tariffs during 2025, giving the market an early signal that a large increase was in the post. This was confirmed when the final tariffs for 2026/27 were published on 30 January 2026. The rises took effect from 1 April 2026, meaning firms had just two months between confirmation and implementation.
The residual charge rose by between 28% and 116% depending on your site's banding. The volume-weighted average increase across all demand users was approximately 64%. Your banding is set by two things: the voltage level of your connection and your agreed supply capacity.
What do TNUoS charge rises mean in practice?
The increase varies by site. A small business on a low-voltage connection is paying around £300 more per year. A mid-sized site on a standard HV connection saw its daily standing charge roughly double, adding several thousand pounds a year. Larger high voltage (HV) and extra-high voltage (EHV) sites saw the steepest rises, with some bands increasing by over 100%.
The per-band table below shows what the increase looks like in pounds and pence.
| Site type | 2025/26 | 2026/27 | Annual increase |
|---|---|---|---|
| Small business (NHH medium band) | £0.76/day (~£278/yr) | £1.60/day (~£583/yr) | +£306/yr |
| HH metered, LV1 (0–80 kVA) | £3.91/day (~£1,427/yr) | £7.28/day (~£2,657/yr) | +£1,230/yr |
| HH metered, LV2 (80–500 kVA) | £6.53/day (~£2,383/yr) | £14.41/day (~£5,260/yr) | +£2,876/yr |
Source: NESO tariff data via Smart Energy UK. TNUoS residual element only.
Banding thresholds changed at the same time
On top of the tariff rise, the banding thresholds that determine which residual band your site falls into were also updated from April 2026. This means some sites were reclassified into a higher band at the same time as every band got more expensive.
If that happened to your site, you're facing two increases at once: a higher rate within the band AND a move to a more expensive band. If your daily standing charge jumped by more than the published percentage increase for your band, a reclassification is likely the reason.
Why the rise happened
Total TNUoS revenue for 2026/27 is £7.61bn, up from approximately £4.3bn in 2025/26. That's a near-doubling in a single year of the amount that transmission owners (the companies that own and maintain the high-voltage network) get back from electricity users.
Transmission investment
The GB transmission network was built for a previous time when cities and industrial areas had nearby power stations. Today, offshore wind generation happens mainly in the north and off the coast, while the south uses the most electricity.
That means there needs to be significant investment in connecting those wind farms and the north-south power corridors. This includes:
- Subsea cables like the Eastern Green Link between Scotland and England
- New onshore substations
- Reinforcements to sections of the network that were never designed for these power flows
What would normally be a multi-decades infrastructure program has been compressed into a few years as the government aims to hit its target to decarbonise the electricity grid by 2030.
The companies that own the grid asked for around £80bn over five years to pay for it all. Not all of that will hit bills immediately, but the cost is being passed through to electricity users via TNUoS, and businesses should expect to continue paying higher bills for this.
The regulatory framework
Ofgem's current price control for electricity transmission (known as RIIO-ET3) covers the five years from 2026 to 2031. This is Ofgem's way of setting how much the companies that own the grid are allowed to charge electricity users.
In December 2025, Ofgem confirmed that transmission owners can recover £46.2bn from electricity users over the five-year period. An earlier draft had put the figure at £48.8bn, so the final number was slightly lower, but it's still far higher than the previous five years. That increase is what drove the April 2026 TNUoS rise.
This is not a one-year spike
The April 2026 increase is not a one-off. According to Drax's analysis of the final tariffs, a typical HV site paying £2,455 per year in 2025/26 is now paying £5,338. By 2030/31, NESO projects that same site's costs reaching £9,005 per year.
At a system level, total TNUoS revenue is forecast to nearly double again, from £7.61bn in 2026/27 to approximately £13.6bn by 2030/31. The next forecast update is due by September 2026. If you're doing medium-term budget planning, assume network costs will keep climbing for the rest of the decade.
What this means for your electricity bill
The increase hits your standing charge, not your unit rate. You can't reduce it by using less electricity or shifting when you use it.
How it appears on your bill depends on your contract. If TNUoS is treated as a pass-through cost, which is common for larger sites on half-hourly meters, the increase went straight onto your bills from April 2026. If your standing charge jumped noticeably in April, that’s probably the reason why.
Most fixed contracts don't cover TNUoS. Look for phrases like "pass-through charges," "third-party charges," or "non-commodity charges" (the parts of your bill that have nothing to do with the price of electricity itself) in your terms. If they're there, your supplier can adjust TNUoS mid-contract even if your unit rate is locked.
For businesses with multiple sites, every meter carries its own daily charge. World Kinect, a global energy management company, found that across large multi-site portfolios, the average increase per meter ranged from £17,000 to £82,500 per year. The largest single-site increase exceeded £300,000.
This isn't a temporary spike. The increase is built into the cost base and further rises are forecast through the rest of the decade.
Who is most exposed
The April 2026 increase affects every GB commercial electricity user, but some are hit harder than others.
| Who | Why they're most exposed | Can they act? |
|---|---|---|
| Multi-site portfolios | Every meter carries its own daily charge, so the increase hits you once per site, so if you have ten meters, that means ten times the increase | Check the banding on each site individually and some may be over-specified |
| Pass-through customers | The increase went straight onto your April bills with no buffer from your supplier | It's already in your costs so make sure you factor it into your budget |
| HH metered sites with high agreed capacity | Higher capacity puts you in a more expensive band, and the per-band increases were steepest for larger sites | Ask your DNO to review your agreed capacity. If it can come down, your daily charge comes down, too |
| Sites in southern GB | Your locational tariff is higher than northern sites because you're further from where most electricity is generated | The locational element is small relative to the residual, meaning you should focus on DUoS and import timing instead |
| Over-specified sites | Your agreed capacity is higher than your site actually needs, so you're paying for a band that doesn't match your usage | Request a capacity review from your DNO or supplier |
| Sites renewing contracts | Your new contract will be priced using the higher TNUoS rates. There's no going back to the old numbers | Use the renewal to negotiate other parts of the bill. TNUoS is fixed, but unit rates and other terms aren't |
What to do this quarter about your TNUoS charges
You can't avoid the TNUoS increase, but there are four things worth doing now, before your next contract renewal.
1. Check your contract treatment
Check whether your current deal has TNUoS pass-through or fixed. If it's pass-through, the increase is already on your bills. Make sure your budget reflects that. If it's fixed, check whether your supplier built in enough headroom for the 2026/27 tariffs or whether they're going to adjust mid-contract.
If you don't know how much of your bill is TNUoS, you won't be able to tell at renewal whether a higher quote is down to network charges you can't change or unit rates you can try to negotiate down further.
2. Confirm your residual band
If your agreed supply capacity is higher than your site actually needs, you could be in a more expensive band than necessary. This is more common than you'd think, especially on sites where demand has dropped since the original connection was set up.
Ask your supplier or your distribution network operator (DNO) to review it. If your capacity comes down, your band drops and so does the daily charge. Understanding how TNUoS is calculated helps you check whether yours is right.
If your site already has a battery that peak shaves, your actual maximum demand from the grid could be well below your agreed capacity. That's worth raising with your DNO when you request a review.
Definition of peak shaving: Peak shaving, in simple terms, is when a battery covers your site's demand spikes so you never pull more than a set amount from the grid. That lower maximum import is what supports the case for reducing your Agreed Supply Capacity. Agreed Supply Capacity is the maximum amount of power your connection is set up to deliver, and the figure that determines which TNUoS band you're in.
3. Review your peak demand exposure
If you have a half-hourly meter, check whether you're managing demand during the most expensive periods. In winter, that means triad-risk windows - these are the cold, dark weekday evenings between November and February when national electricity demand peaks. Year-round, it means DUoS red-band periods, typically the late afternoon, when distribution charges are at their highest.
The locational TNUoS saving from managing peaks is small on its own. But when you add up the effect across TNUoS, DUoS, and your import costs, it starts to make a difference. If you don’t monitor this regularly, there is a danger you’re paying more than you need to.
4. Reduce the costs you can still move
Your TNUoS bill is fixed but the rest of what you pay for electricity isn't. Battery scheduling, solar self-consumption, import timing, and trading revenue all bring down what you spend on the parts of the bill you can influence via your energy usage.
They won't touch your TNUoS bill, but they improve the overall picture, especially once you understand which non-commodity charges on your bill actually respond to what your site does.
How GridVolt can help reduce bills as TNUoS rises
GridVolt can't cut your TNUoS residual, that's fixed. But we can reduce other parts of your electricity bill and, in GB, add a revenue stream on top.
- GridTrade: Earn trading revenue from wholesale and balancing markets and stay with your existing supplier.
- Energy Manager: Software, compatible with most batteries, that decides when to charge, discharge, and import based on your actual tariff, so you pay less for the same electricity.
Here’s a modelled scenario to show the difference we can make.
We ran GridVolt's scheduling engine against nine months of Octopus Agile pricing data (a half-hourly variable electricity tariff) for South England. The period of time covered was April 2024 to January 2025. The analysis used a modelled commercial load profile consuming approximately 620 MWh per year, representative of a mid-sized commercial site.
The site's electricity consumption was identical in all three scenarios. The only thing that changed was when and at what price the electricity was purchased.
| Standard fixed contract | Wholesale tariff, no battery | Wholesale tariff + GridVolt scheduling | |
|---|---|---|---|
| Effective rate | ~24p/kWh | 18.5p/kWh | 14.4p/kWh |
| Annual electricity cost | ~£149,000 | ~£115,000 | ~£89,000 |
| Annual saving vs standard | - | ~£34,000 | ~£60,000 |
| Price spike protection | Yes (rate is fixed) | No (fully exposed) | Yes (battery absorbs spikes) |
Notes: Modelled scenario using a 400kWh / 200kW battery system. Based on Octopus Agile Region C (South England) pricing, April 2024 to January 2025. Battery cost assumed at £220/kWh installed. Standard commercial rate based on published UK business electricity averages for 2025–2026. All prices exclude VAT.
For companies, the middle column is the trap. A wholesale tariff on its own looks cheaper on paper, but it leaves you fully exposed to price spikes. The battery removes that risk and GridVolt's scheduling captures the value. The result is a 40% reduction in effective import cost, with the battery investment paying for itself in under four years.
Contact GridVolt for a compatibility check and a custom review of your tariff, load profile, and existing energy assets, including solar panels and battery storage. We'll let you know what the savings and revenue potential look like on your specific site.