What are TNUoS and DUoS charges on my business bill?
TNUoS pays for the national high-voltage grid and DUoS for your local distribution network. On fixed contracts they are bundled into your standing charge and unit rate; on pass-through contracts they can show as separate lines, and DUoS varies by region and time band.
TNUoS and DUoS are the network charges built into your electricity bill. TNUoS (Transmission Network Use of System) pays for the high-voltage national grid. DUoS (Distribution Use of System) pays for the local cables and substations that reach your premises.
Where you see them
On a fixed-price contract you typically will not see either as a line item. They are bundled into your standing charge and unit rate. On a pass-through or flexible contract they can appear separately, and larger half-hourly sites are most likely to see this. See pass-through vs fixed charges.
How they work
| TNUoS | DUoS | |
|---|---|---|
| Pays for | National high-voltage grid | Local network of cables, poles and substations |
| Set by | The national system operator's methodology | 14 regional distribution operators |
| Depends on | Your zone, meter type and capacity band | Region and, for larger sites, the time of use |
| Time bands | No | Red, amber and green on half-hourly meters |
The red band is the dearest, amber is medium and green is cheapest. Each distribution operator sets its own band times, so check your network operator's published charging statement for the hours that apply in your area.
Why people mention them now
Comparison site MoneySuperMarket reported in March 2026 that TNUoS was expected to rise by about 60 per cent from April 2026, from roughly £16 to £31 per MWh, mostly via standing charges. These are that publisher's estimates, not official figures from Ofgem or the system operator, and not a figure for your bill.
A worked example
1 MWh is 1,000 kWh, so a site using 10,000 kWh uses 10 MWh. At the publisher's reported average rates, illustratively:
- Before: 10 × £16 = £160
- After: 10 × £31 = £310
- Rise: £150 a year before VAT
Actual impact varies because TNUoS is mostly a fixed charge by site, not by units used. A small site with low use may feel it more per kWh, so read your standing charge carefully.
What you can do
- Ask in a quote whether network charges are fixed or pass-through, and what happens if they change in the term.
- If you have a half-hourly meter, ask about moving use out of red-band hours. See half-hourly meters.
- Check your agreed capacity is no higher than you need. See capacity and kVA charges.
Do they apply to gas?
No. TNUoS and DUoS are electricity charges. Gas has its own transportation charges, which are included in gas prices and are set by the gas network companies. If you want to see how they fit into the whole bill, our page on reading your business energy bill shows where each element lands.
Who sets them?
The rules are approved by the energy regulator, but the charges themselves are calculated by the network owners and the system operator and published in advance. Suppliers then decide how to present them in your price, which is why two quotes with the same network costs can look different.
Next steps
The wider picture is in non-commodity charges explained. For definitions see the TNUoS and DUoS glossary entries.
Sources
General information only. Energy prices, rules and supplier terms change; check the latest position with your supplier, Ofgem or the Energy Ombudsman before you act.