TNUoS and DUoS charges explained -How will the increases affect your business? 

TNUoS and DUoS charges cover the cost of getting electricity from power stations, across the high‑voltage grid, and through local cables to your premises. 

From April 2026, they’re set to make up a much bigger slice of your business energy bills as these non‑commodity costs will increase to help fund the upgrades needed to connect renewable energy sources (like wind farms) to the National Grid. 

Here’s all you need to know about what these charges are and how the increased costs could affect your business. 

Five‑point summary for our guide to TNUoS and DNUoS charges 

1. TNUoS and DUoS are network charges that pay for the national grid and local cables that deliver electricity to your business, and now make up a large share of non‑commodity costs. 
2. From April 2026, TNUoS charges in particular will rise, with typical rates for many business users roughly doubling and standing charges hit hardest. 
3. Your location, meter type and capacity band determine how much TNUoS and DUoS you pay, so two similar‑sized businesses in different regions can face very different bills. 
4. You can’t avoid TNUoS and DUoS altogether, but you can reduce their impact by cutting consumption, shifting usage away from peak times, and optimising your capacity. 
5. Bionic can help you make sense of rising non‑commodity charges, compare contracts from leading business energy suppliers and find a deal that works for how your SME actually uses power. 

What are TNUoS and DUoS charges? 

Transmission Network Use of System (TNUoS) and Distribution Use of System (DUoS) charges are the fees your supplier pays to use the national electricity networks. Known as non-commodity charges, these costs are then built into what you pay for business electricity.  

TNUoS covers the cost of the high‑voltage transmission grid, including long‑distance pylons and cables. DUoS covers the cost of your local distribution network, including the substations, poles and underground cables that connect to your premises. 

Think of it like this - TNUoS is the cost of using the "motorways" that get electricity across the country, while DUoS is the cost of using the local "A-roads and streets" that take this electricity to your door. 

For most small and medium‑sized businesses, these network costs are wrapped into your standing charge and unit rate. You won’t see “TNUoS” or “DUoS” as separate line items unless you’re on a pass‑through or flexible tariff.  

But even if they’re hidden in the background, they still have a direct impact on what you really pay per kWh. 

Where do TNUoS and DUoS sit on your bill? 

Your business energy bill is made up of several costs, including wholesale costs, network charges and policy costs, plus supplier margins and VAT.  

TNUoS and DUoS sit in the “non‑commodity” bucket, which is everything you pay for that isn’t the actual energy itself. 

• TNUoS charges - Usually recovered through your daily standing charge and, for larger users, can be linked to peak‑demand periods on the transmission system. 
• DUoS charges - Usually recovered through a mix of standing charge and unit rate, with costs that vary by region and by time of day. 

On a typical fixed‑price business energy contract, suppliers bundle non‑commodity charges into the unit rate and a fixed daily standing charge. This means you see a simple price even though a growing share of it is made up of network costs like TNUoS and DUoS. 

What are non‑commodity costs?

Non‑commodity costs are all the charges that sit on top of the wholesale electricity price, including network costs (TNUoS, DUoS, BSUoS), environmental levies and social policy schemes.  

Over the last decade, these non‑commodity elements have grown steadily, to the point where they can now account for as much of your bill, if not more than, than the wholesale power itself. 

Ofgem’s Targeted Charging Review (TCR) and recent price control decisions mean that a greater share of network costs will be recovered through fixed residual charges. These are shown as higher standing charges for businesses of all sizes.  

That’s why keeping an eye on non‑commodity changes for April 2026 is just as important as watching wholesale price trends. You can find out more about Ofgem’s TCR in our guide to standing charges. 

TNUoS charges explained in more detail 

TNUoS stands for Transmission Network Use of System and recovers the cost of building, operating and maintaining the high‑voltage transmission grid in England, Wales, Scotland and offshore.  

These are the big pylons and long‑distance circuits that move power from generators and interconnectors to local distribution networks. 

Key points about TNUoS: 

• Paid by suppliers (and some generators) based on how their customers use the transmission system. 
• Historically driven by winter peak “Triad” demand for large half‑hourly metered sites, with charges based on three half‑hour periods of highest system demand between November and February. 
• Now heavily influenced by fixed residual charges set under the Targeted Charging Review, allocated by meter type and capacity band rather than pure consumption. 

As a smaller business on a standard fixed contract, you won’t need to calculate your own TNUoS charges – your supplier will build them into your quoted standing charge and unit rate – but any step‑change in TNUoS tariffs will still feed directly through to what you pay. 

DUoS charges explained in more detail 

DUoS stands for Distribution Use of System. This covers the cost of running the local distribution networks that move electricity from the transmission grid to homes and businesses. These networks are owned and operated by regional Distribution Network Operators (DNOs), and DUoS is how they recover their allowed revenue. 

Key points about DUoS: 

• Rates vary by region, because each DNO has different costs, network layouts and investment needs. 
• For many sites, DUoS is charged per kWh, with different prices at different times of day (often represented as red, amber and green time bands). 
• Day and night charges, plus maximum import capacity charges for larger users, all sit within the DUoS framework. 

If you run energy‑intensive equipment during peak evening hours in a high‑cost DUoS regi-on, the distribution element of your bill can be significantly higher than a similar business that operates mainly in off‑peak bands in a lower‑cost area. 

How big is the increase in TNUoS and DUoS costs? 

From April 2026, non‑commodity electricity costs are set to rise sharply, driven largely by higher network charges. Transmission charges in particular are expected to jump for business users as new TNUoS tariffs and price control decisions take effect. 

What’s changing? 

• TNUoS costs - Average TNUoS rates for half‑hourly electricity sites will rise by around 60%. The average rate will move from about £16 per MWh to roughly £31 per MWh from April 2026. For gas, the increase will be 40%.
• Non‑commodity share - The proportion of electricity costs made up from TNUoS alone could increase from around 8% to more than 13% for a typical half‑hourly consumer, and up to 25% for very high‑voltage sites. 
• Fixed residual charges - Much of this increase will come through higher fixed residual TNUoS charges in standing charges, rather than a simple uplift to unit rates. 

Some industry analysis suggests that, after the April 2026 changes, even the smallest business sites could be paying several hundred pounds more per year in TNUoS‑related standing charges, while energy‑intensive sites could see six‑figure annual increases in combined TNUoS and DUoS costs. 

What does the increase in non-commodity charges mean for UK businesses? 

From April 2026, transmission and network costs for electricity customers are set to rise significantly. Securing a fixed-rate contract could help protect against any future increases. 

For most SMEs, the headline impact of April 2026 network changes will be higher standing charges and a higher overall cost per kWh, even if your usage stays the same.  

Because these are regulated non‑commodity costs, there’s little you can do to avoid the uplift altogether, but you can reduce the impact by focusing on efficiency and choosing the right type of contract. 

In practice, this means that two similar‑sized businesses in different regions, or with different operating hours, could see very different total bills once higher TNUoS and DUoS charges are factored in, even if their agreed unit rates look similar on paper. 

What’s the difference between TNUoS and DUoS? 

TNUoS and DUoS make up most of your network charges. Although both are regulated by Ofgem, they are set by different entities. This is why tariffs from different suppliers, or in different regions, can produce different bill totals for businesses. 

How TNUoS and DUoS charges vary by region and meter type 

Your exact TNUoS and DUoS costs depend on a few things, including: 

• Your region - Different TNUoS “zones” and DUoS regions have different tariffs, reflecting the cost of serving that part of the country. 
• Your meter type - Half‑hourly (HH) meters and extra‑high‑voltage sites sit in different TCR bands to smaller non‑half‑hourly (NHH) meters. 
• Your capacity - Larger sites with higher agreed supply capacity pay more in fixed network and capacity charges. 

If you run a small retail unit or office in a major city, your network costs will look very different to a manufacturing site on an industrial estate. From April 2026, the gap between lower‑band and higher‑band sites is expected to widen even further. 

Can you reduce TNUoS and DUoS costs? 

You can’t opt out of paying TNUoS and DUoS, but you can make choices that reduce their impact on your overall bill. The main levers are usage patterns, efficiency and capacity management. 

Practical steps include: 

• Shifting usage away from peak DUoS time bands by running energy‑intensive processes earlier in the day or later at night, where it’s safe and practical to do so. A time-of-use tariff could be your best option in this instance. 
• Reducing overall consumption through energy audits, LED lighting, efficient heating and cooling, and smarter controls. 
• Reviewing and optimising your agreed supply capacity so you’re not over‑paying for headroom you never use. 
• Considering on‑site generation or storage (like solar PV and batteries) to reduce reliance on the grid during peak times. 

Even for smaller SMEs on fixed‑price contracts, a focused energy‑efficiency plan can offset some of the April 2026 uplift in non‑commodity charges by cutting the amount of energy you use.  

Although switching to a fixed rate guarantees the unit rate and standing charge you pay for the duration of your contract, this doesn’t fix the non-commodity costs. Even so, locking in rates early can protect you from market volatility, and a lower unit rate may help to offset a hike in TNUoS and DUoS charges. 

How Bionic can help 

Comparing business energy deals on your own can be time‑consuming, especially when more of the cost comes from complex non‑commodity and network charges that you never see broken out on the quote.  

Bionic’s tech‑enabled team can quickly compare deals from a panel of trusted suppliers, explain how changes to TNUoS and DUoS could affect what you’ll really pay, and help you lock in a contract that fits the way your business uses energy. 

As the April 2026 non‑commodity changes approach, Bionic can also talk you through options like fixed tariffs versus pass‑through tariffs. This can help you decide whether it makes sense to secure prices early or build more flexibility into how your network costs are charged.