DUoS
What is DUoS?
DUoS, short for Distribution Use of System, is the charge for using the local electricity distribution network, the lower-voltage wires and substations that carry power the final stretch to your premises. It is one of several network and policy costs bundled into a business electricity bill, paid to the regional Distribution Network Operator that owns and maintains those wires. Most businesses never see DUoS as a separate line, because it is folded into the unit rate, but on larger half-hourly supplies it is often itemised, and becomes a meaningful, and partly controllable, cost.
On this page
DUoS is one of the network charges that explain why your electricity costs more than the wholesale price of the power itself. It sits alongside transmission and balancing charges, and it is set regionally rather than nationally, which is why two identical businesses in different parts of the country can pay different network costs.
What DUoS is
DUoS is the charge for using the local distribution network: the regional grid of lower-voltage cables, substations and transformers that takes electricity from the high-voltage transmission system and delivers it to homes and businesses. Every unit you draw travels across that network, and DUoS is how the cost of running and maintaining it is recovered.
It is distinct from the charge for the energy itself. Your unit rate pays for the power, and DUoS pays for the local wires that bring it to your door.
What it pays for
DUoS funds the operation, maintenance and upgrading of the distribution network in your region. That covers everything from repairing faults and replacing ageing equipment to reinforcing the network so it can carry more load as demand grows.
It does not pay for the national high-voltage grid, which is recovered through a separate transmission charge, nor for the energy you consume. It is specifically the cost of the last leg of the journey.
Who sets it
DUoS charges are set by the regional Distribution Network Operator, the company that owns and runs the wires in your area, within a framework regulated by Ofgem. Because there are several operators across Great Britain, each covering a different region, the charges vary from place to place.
That regional variation is built into your rates. A business in one operator area can face higher network costs than an identical business elsewhere, purely because of where it sits.
How it is charged
For most smaller businesses, DUoS is simply absorbed into the single unit rate the supplier quotes, so it is paid without ever being seen. For larger sites on a half-hourly meter, it is charged in more detail, with separate elements for the units consumed, the capacity reserved, and in some cases a fixed daily charge.
The capacity element links to your authorised supply capacity, also called Maximum Import Capacity (MIC), the amount of kVA you have reserved, which is part of why right-sizing your capacity matters for larger supplies.
Red, amber and green bands
For half-hourly supplies, the per-unit part of DUoS is split into time bands, usually labelled red, amber and green. Red covers the busiest periods, typically weekday late afternoons and early evenings, and carries by far the highest rate. Amber covers the shoulder periods, and green covers nights and weekends, where the charge is lowest.
The gap between bands can be large, so when you use electricity, not just how much, affects this part of the bill. Shifting demand out of the red band is where the savings sit.
How it appears on your bill
If you are on a fully bundled rate, you will not find DUoS as its own line; it is part of the unit rate. If you are on a half-hourly or pass-through arrangement, it is often itemised, sometimes broken down by the red, amber and green bands, so you can see exactly what the network is costing you.
Either way it is a real cost you are paying. The difference is only whether it is visible or hidden inside a single number.
Managing your DUoS costs
For a half-hourly site, the two main levers are timing and capacity. Moving flexible electricity use out of the expensive red band and into amber or green reduces the per-unit charge, and reviewing your reserved capacity so you are not paying for far more kVA than you use can trim the capacity element.
These are genuine, controllable savings, which is unusual for a network charge. For a fuller treatment, our article on DUoS charges explained goes deeper into how the bands and capacity work.
Who it affects most
Every electricity user pays DUoS, but it matters most to larger, half-hourly metered businesses, where it is itemised, time-banded and large enough to manage. For a small business on a bundled rate, DUoS is simply part of the unit rate and not something to act on directly.
For the bigger picture of how network and policy costs build up a commercial bill, our business electricity page sets out the components.
Frequently asked questions
What is DUoS?
DUoS stands for Distribution Use of System. It is the charge for using the local electricity distribution network, the lower-voltage wires and substations that deliver power the final stretch to your premises, paid to the regional Distribution Network Operator.
What does DUoS pay for?
It funds the operation, maintenance and upgrading of the local distribution network in your region, such as repairing faults, replacing equipment and reinforcing the network. It does not pay for the national transmission grid or for the energy you consume.
Who sets DUoS charges?
They are set by the regional Distribution Network Operator that owns the wires in your area, within a framework regulated by Ofgem. Because there are several operators across Great Britain, the charges vary by region.
Is DUoS shown on my electricity bill?
On a fully bundled rate, no, it is absorbed into the unit rate. On a half-hourly or pass-through arrangement it is often itemised, sometimes broken down by time band, so you can see what the network is costing you.
What are the red, amber and green DUoS bands?
For half-hourly supplies, the per-unit DUoS charge is split by time of use. Red covers the busiest periods, typically weekday late afternoons and early evenings, with the highest rate. Amber covers shoulder periods, and green covers nights and weekends, with the lowest rate.
Can I reduce my DUoS charges?
On a half-hourly site, yes. Moving flexible electricity use out of the expensive red band into amber or green lowers the per-unit charge, and reviewing your reserved capacity so you are not paying for unused kVA can reduce the capacity element.
Does DUoS vary by region?
Yes. Each Distribution Network Operator sets its own charges for its area, so two identical businesses in different regions can pay different network costs purely because of location.
What is the difference between DUoS and TNUoS?
DUoS is the charge for the local distribution network that delivers power to your premises. TNUoS is the charge for the national high-voltage transmission system that carries power across the country. Both appear within a business electricity bill but cover different parts of the network.
Does DUoS apply to gas?
No. DUoS is an electricity network charge only. Gas has its own separate transportation and distribution charges.
How is DUoS charged to small businesses?
For most small businesses it is simply built into the single unit rate the supplier quotes, so it is paid without being shown separately. The detailed, time-banded version applies to larger half-hourly supplies.
What is the capacity element of DUoS?
On larger supplies, part of DUoS is charged on the capacity you have reserved, linked to your authorised supply capacity, also called Maximum Import Capacity, in kVA, rather than on the units you use. Reserving more capacity than you need means paying more than necessary.
Who does DUoS affect most?
Larger, half-hourly metered businesses, where DUoS is itemised, time-banded and big enough to actively manage. For a small business on a bundled rate it is part of the unit rate and not something to act on directly.
Network operator charging statements (neso.energy) · Ofgem network charging guidance (ofgem.gov.uk)