Energy Suppliers

UK Energy Suppliers: The Full Guide to Who Supplies Your Gas and Electricity

The UK's household energy market is smaller than it was, and more concentrated. There are 23 domestic energy suppliers and 72 business energy suppliers currently active in the market, and six large companies dominate the domestic market with 91 per cent market share, with Octopus now the largest electricity supplier in Great Britain¹. Behind those suppliers sits a physical system in which gas still matters: gas accounted for 33.3 per cent of electricity generation by Major Power Producers in the three months to November 2025². The UK government's most recent position is that "The UK continues to have robust energy supplies."³

The market has also been tested hard. The high gas price rise forced several energy suppliers out of the market⁴, and 29 suppliers failed between July 2021 and May 2022, affecting nearly four million households⁵. From 1 October 2026 the price cap for a typical dual fuel household paying by direct debit rises by £60 to £1,723 per year⁶. This guide sets out who the suppliers are, what they are licensed to do, what happens when they fail, and what the whole arrangement means for a household that wants more control over its own energy.

Who supplies gas and electricity: the market at a glance

A domestic energy supplier is a company licensed to sell gas and electricity to households. It is the name on your bill, the company that sets your tariff, takes your payments and handles your complaints. It is not the company that owns the cables and pipes that reach your home: those belong to regional network operators, and your supplier pays to use them. You can find out who your network provider is via the Energy Networks Association website⁷.

The structure matters because it divides responsibility. If your power cuts out, that is a network matter, not a supplier matter. If your bill is wrong, your credit balance goes missing or your tariff is mis-sold, that is a supplier matter, and it is the supplier named on your bill that a dispute must be raised against⁸. Ofgem, the regulator, licenses suppliers and sets the rules they must follow, while the Energy Ombudsman handles complaints that suppliers cannot resolve.

The market itself has two parts. Great Britain, meaning England, Scotland and Wales, operates as one market with one set of suppliers and one regulator. Northern Ireland runs a separate market with its own suppliers, its own price regulation and its own consumer body, covered later in this guide. The number of suppliers has contracted sharply: Ofgem's State of the Market report counts 23 domestic suppliers active today¹, against the dozens trading before the gas price crisis. For a household, the practical effect is fewer names to choose from, but the same division of duties between the company that sells energy and the company that delivers it.

How many suppliers are there, and who are the Big Six?

The "Big Six" is the name given to the six large legacy suppliers: Centrica plc, the parent company of British Gas, E.ON UK, Scottish and Southern Energy (SSE), RWE npower, EDF Energy and ScottishPower⁹. The label dates from a period when those firms supplied almost every home in Great Britain. As of September 2016, 14 per cent of domestic consumers received their electricity from suppliers other than the six large energy companies¹⁰, so the group's hold was already loosening a decade ago.

Today the picture is more mixed. Six large companies still dominate the domestic market with 91 per cent market share, but Octopus is now the largest electricity supplier in Great Britain, and the second largest gas supplier¹. Some of the original Big Six names no longer exist as independent retail businesses in the form they once did, and households that think of themselves as customers of a familiar brand may in fact be supplied by a different company altogether. The Big Six energy suppliers page traces what became of each firm, and who owns which energy supplier sets out the parent companies behind the names on bills.

The wider supplier count depends on who is counting and when. Ofgem counts 23 domestic suppliers and 72 business energy suppliers currently active¹. Which? rated 14 energy suppliers in its 2026 analysis of the Great Britain market¹¹. The National Audit Office counted 30 suppliers on the Energy Price Guarantee scheme in November 2024¹². The differences reflect dates and definitions, but the direction is clear: the market has consolidated since 2021, and the challenger energy suppliers that remain are fewer and generally better capitalised than those that failed.

What a supplier actually does: the hub model

An energy supplier is responsible for providing energy to homes and businesses¹³. In practice that means buying energy wholesale, arranging its transport across the networks, setting tariffs, billing, collecting payments and handling the customer relationship. The market was designed with suppliers as the primary interface between energy consumers and the energy system¹⁴, which is why every obligation, scheme and protection aimed at households lands on the supplier first.

That hub role carries a long list of legal duties beyond selling energy:

• Under the Feed-in Tariff scheme, a licensed electricity supplier's market share is determined by the amount of electricity it supplies to customers in Great Britain, less exempt supplies to qualifying energy intensive industries, expressed as a percentage of the total supplied by all licensed suppliers¹⁵.
• The government is updating the Warm Home Discount supplier reconciliation process so that supplier obligations are settled against actual energy volumes supplied¹⁶.
• Under the legislation that created the domestic electricity price reduction scheme for Great Britain, licensed electricity suppliers providing domestic supply must take all reasonable steps to become a party to the designated scheme as soon as is reasonably practicable¹⁷.

For a household, the hub model has one central consequence: your supplier is your single point of contact and accountability, even when the underlying failure lies with a broker, a meter operator or a third party working on the supplier's behalf. If something goes wrong, the complaint goes to the supplier named on the bill, and only that company. That is also why the correct company name matters when a dispute reaches the Energy Ombudsman: the dispute must be raised against the supplier that matches the name written on the account holder's bill⁸.

The price cap: how your bills are limited, and where it stands

The price cap is Ofgem's limit on the unit rates and standing charges a supplier can set on default tariffs. The Welsh Government's guidance states the purpose plainly: "Ofgem, the UK's energy regulator, sets the price cap to protect people from a 'loyalty penalty.'"¹⁸ In other words, the cap exists to stop suppliers charging loyal, non-switching customers more than everyone else. It is not a cap on your total bill: it caps the rates, so a household that uses more energy pays more.

The cap moves every quarter. It stood at £1,758 before April 2026, was set at £1,641 for 1 April to 30 June 2026¹⁹, and rises by £60 to £1,723 per year from 1 October 2026 for a typical dual fuel household paying by direct debit⁶. Bills in 2025 based on the price cap stayed between £1,700 and £1,900¹⁸. For households paying when the bill arrives rather than by direct debit, the typical annual cost under the cap is higher, at £1,772¹⁸. For historical context, the cap fell to £1,834 in Q4 2023 before a planned increase to £1,928²⁰.

The cap also varies by region, because network costs differ. For 1 July to 30 September 2026, the benchmark maximum annual electricity bill at 2,500 kWh on a single-rate meter ranged from £801.74 in the Southern region to £824.03 in the Northern region, with standing charges ranging from £172.77 to £223.48²¹.

Regional levels for 1 October to 31 December 2025 show the same pattern: an Eastern region household on standard credit faced £196.61 a year in standing charges before any consumption and £1,023.11 at 3,100 kWh single-rate, while a Midlands household faced £212.30 and £1,011.26²².

How roughly 30 energy firms went under

Between July 2021 and May 2022, 29 energy suppliers failed, affecting nearly four million households in the UK⁵. The House of Commons Public Accounts Committee traced the cause to the lack of financial resilience within many energy suppliers combined with the rise in wholesale prices⁵. Many of the failed firms had built their business on a simple bet: they sold energy to households at fixed rates while buying it wholesale at prices that could move against them, and they held too little capital to absorb the loss when wholesale gas prices surged.

The high gas price rise forced several energy suppliers out of the market⁴, and the failures were not confined to small firms. Even the large incumbents felt the pressure: ScottishPower stated in May 2022 that "our retail business is losing money during what is an incredibly difficult time for many of our customers"²⁴. The episode exposed a structural weakness in the market's design. Suppliers had been allowed to grow quickly with thin margins, sell tariffs below the eventual cost of the energy they promised to deliver, and hold far less capital than the risks they were running required.

The consequences fell partly on bill-payers. When suppliers failed, the costs of moving customers to new suppliers and honouring their credit balances were recovered through levies on everyone's bills, and the Energy Price Guarantee scheme that followed the crisis involved 30 suppliers¹². The regulatory response has been to tighten the rules on capital and hedging, which is one reason the supplier count has fallen and the market has consolidated. The energy supplier failures page lists every collapse, and energy supplier financial resilience rules explains what suppliers must now hold.

Your account and credit if your supplier collapses

The first thing to know is that your energy does not stop. Ofgem's guidance is explicit: "If your energy supplier goes out of business because of financial problems, you will still have electricity and gas supplied to your home or business. Your energy supply will not be cut off."²⁵ Ofgem runs a supplier of last resort process, appointing another licensed supplier to take on the failed company's customers. As Ofgem puts it: "You do not need to do anything if your current supplier goes out of business. We'll automatically move you to a new supplier, and make sure your energy supply is not interrupted."²⁵

Your money is protected too. Under the Energy Supply Administration Order framework, "your credit balance will be protected unless you are a business"²⁵. The new supplier should honour the credit you had built up, typically by carrying it forward on your new account or refunding it. Practical steps help: take a meter reading on the day you hear the news, and keep your most recent bills and statements so the balance can be verified against your own records.

Two things to watch. First, the tariff you are moved to is a deemed contract, usually the new supplier's standard variable rate, which is capped but rarely the cheapest option, so you are free to switch away without exit fees. Second, the scale of these events has been large: the National Audit Office reported that 12 out of 101 non-domestic suppliers on the Energy Bills Relief Scheme were approved to exit the scheme after a supplier-by-supplier review of payments¹², a reminder that supplier-by-supplier scrutiny of public money followed the crisis. The supplier of last resort page explains the process in full.

Big providers, smaller rivals and white label brands

The domestic market now has three broad tiers. The first is the large suppliers, the descendants of the Big Six plus Octopus, holding 91 per cent of the domestic market between six companies¹. The second is the challenger tier: smaller licensed suppliers competing on price, service or specialism, of which Which? rated 14 in its 2026 analysis¹¹. The third is the white label tier, brands that sell energy under a familiar name while a licensed supplier operates behind the scenes; the white label energy brands page explains how those arrangements work and whose licence sits behind each brand.

New entrants still appear. Tesla Energy Ventures Limited was granted a licence authorising it to supply electricity to domestic and non-domestic consumers in Great Britain, with the licence applying to electricity supply activities in Great Britain only²⁶. That territorial limit is worth noting: a Great Britain licence does not extend to Northern Ireland, and vice versa.

Which type fits which household depends on what the household values. Large suppliers offer scale, long track records and full product ranges; challengers often compete on service or specialist tariffs; white labels offer brand convenience but the underlying obligations sit with the licensed supplier. Ofgem's consumer satisfaction work now publishes two indicators of customer satisfaction for seven energy supply groups, covering overall satisfaction with the supplier and satisfaction with the customer service received²⁷. The underlying survey drew on large samples: British Gas (1015 respondents), EDF Energy (371), E.ON and E.ON Next (556), Octopus Energy (796), OVO Energy (373), Scottish Power (257) and Utilita (130)²⁸. The energy supplier customer service ratings page carries the detail.

Eco tariffs and flexible time based pricing

Green tariffs are now mainstream, but understanding of them is patchy. Ofgem's 2021 consumer survey found that half of all consumers, 51 per cent, reported being on a green tariff currently or said they were likely to switch to one, with a further 24 per cent saying they were likely to switch to one in the next five years²⁹. Yet 23 per cent of consumers answered "don't know" when asked what a green tariff actually is²⁹. Take-up also splits by engagement: 34 per cent of engaged consumers were on or likely to take a green tariff, against 16 per cent of disengaged consumers, and 31 per cent of 16 to 34 year olds²⁹.

What a "green" tariff means varies by supplier, which is why scrutiny matters. In March 2026, Which? asked energy suppliers in Great Britain to tell it exactly how they sourced their renewable energy, and rated 14 suppliers in its analysis¹¹. The differences between suppliers, including how much is genuinely sourced versus bought as certificates, are set out on the green energy tariffs and fuel mix disclosure pages.

Time-of-use rates are the other big shift in what suppliers sell. Instead of one flat unit rate, these tariffs charge more at peak hours and less overnight, which suits households with an electric vehicle, a home battery or flexible washing and heating habits. Ofgem's research found 9 per cent of consumers said they were very likely to get an electric vehicle in the next five years²⁹, and suppliers have built EV-specific tariffs around that demand. For a household generating or storing its own energy, time-of-use rates change the economics of self-consumption, because shifting use into cheap hours reduces what has to be bought at all.

Northern Ireland runs its own energy market

Northern Ireland is not part of the Great Britain market. It has its own suppliers, its own network arrangements and its own consumer body, and Ofgem's price cap does not apply there. Electricity supply is dominated by Power NI, SSE Airtricity, Click Energy and Budget Energy, while gas is supplied regionally, with firmus energy in the Greater Belfast and Ten Towns networks and SSE Airtricity in the Gas to the West area.

Prices change by supplier announcement rather than by a quarterly cap. firmus energy raised gas prices by 8.9 per cent in Ten Towns and 12.5 per cent in Greater Belfast from October 2026³⁰. A tariff change for SSE Airtricity in the Gas to the West area was scheduled for 1 October 2026³¹. The Consumer Council for Northern Ireland offers an energy price comparison tool to compare electricity and gas tariffs for all suppliers in Northern Ireland³¹, and it publishes scheduled tariff changes so households can check the impact before they arrive.

Support arrangements differ too. The Warm Home Discount does not apply in Northern Ireland in the same way as in Great Britain, and advice routes are local: nidirect notes that suppliers refer customers who are struggling to pay bills to organisations like Advice NI, which offers free, independent debt advice³². For a Northern Ireland household, the practical differences are real: different suppliers, different price mechanisms and different sources of help, all covered in detail on the energy suppliers in Northern Ireland page.

How suppliers make money, and when they lose it

A supplier's core business is buying energy wholesale, at prices that move, and selling it to households at rates fixed for months at a time. The margin between those two positions is the retail profit, and it is thin and fragile. The 2021 to 2022 crisis showed what happens when the gap closes from the wrong side: 29 suppliers failed between July 2021 and May 2022 for want of financial resilience against rising wholesale costs⁵, and even ScottishPower, one of the largest, stated publicly that its retail business was losing money during the cost of living crisis²⁴.

Suppliers also carry scheme obligations that shape their costs. The Warm Home Discount reconciliation is being updated so supplier obligations are settled against actual energy volumes supplied¹⁶, which ties what a supplier owes more closely to what it actually sold. Under the domestic electricity price reduction scheme legislation, licensed suppliers must take all reasonable steps to become a party to the designated scheme as soon as is reasonably practicable¹⁷.

For a household, the economics explain two things. First, why suppliers push direct debit, smart meters and online accounts: each reduces their cost to serve. Second, why the market is now concentrated: thin margins, capital requirements and scheme obligations favour scale, which is why six companies hold 91 per cent of the domestic market¹. The energy supplier profits and margins page carries the figures.

Changing supplier and debt restrictions

Switching is the household's main lever in this market, and the rules around debt are more permissive than many assume. Prepayment meter customers have a specific protection under the Debt Assignment Protocol: PPM customers with less than £500 debt per fuel can switch suppliers³³. Beyond that, suppliers can review your current payments and debt repayments if you are struggling³⁴, so debt does not have to grow unchecked before you act.

The wider switching framework is covered across this site: the energy switch guarantee, exit fees when switching, the cooling off period, and switching with prepayment debt. The mechanics are settled: supply is not disrupted when you switch, and the process runs to fixed timescales.

The open question is engagement. In 2018 the Department determined that bills should be capped following findings from the Competition and Markets Authority that 70 per cent of customers of the six largest energy firms were on default tariffs⁵. The price cap now protects those default tariffs, but the underlying pattern, most households not actively choosing, is what the cap was built to correct. A household that checks its tariff once a year and switches when it is beaten is doing the one thing this market rewards.

Hardship funds and vulnerability support

Suppliers owe more than energy to customers in difficulty. Ofgem's guidance is that energy suppliers give you access to financial support, called "hardship funds", and that supplier schemes and grants can fund paying off energy debt³⁴. These funds, often run as charitable trusts, exist across the major suppliers, and the supplier hardship funds and trusts page lists what each operates and how to apply.

Referral is part of the duty. In Northern Ireland, suppliers refer customers who are struggling to pay bills to organisations like Advice NI, which offers free, independent debt advice³². The same principle applies across Great Britain: a supplier that knows a customer is struggling is expected to act on it, through payment reviews, hardship funds, or referrals to independent advice. The what suppliers must do for vulnerable customers page sets out the obligations in full.

For a household, the practical points are these. Hardship support is not automatic: it usually has to be asked for, and evidence of circumstances may be needed. Debt on an energy account grows fastest in winter, so contacting a supplier before arrears build gives more options than after. And the Priority Services Register exists alongside hardship funds for households that need extra support in an outage or emergency. None of this is charity beyond obligation: suppliers are required to identify and support customers in vulnerable situations, and the regulator checks that they do.

Ofgem, the Ombudsman and the consumer bodies

The regulatory architecture has three layers. At the top sits the Gas and Electricity Markets Authority, which is the controller for consultation purposes and is referred to simply as Ofgem³³. Ofgem licenses suppliers, sets the rules in its supply licence conditions, administers the price cap and polices conduct. Its remit also extends to heat networks: the Energy Act 2023 named Ofgem as the regulator for heat networks in Great Britain³⁵, which brings households on communal heating under the same regulator as everyone else.

The second layer is redress. Ofgem's complaints route requires a household to complain to the supplier first, giving it a chance to resolve the matter¹³. If the supplier cannot or will not, the Energy Ombudsman can decide, and the dispute must be raised against the correct supplier, matching the company name written on the account holder's bill⁸. The complaining about an energy supplier page walks through the process and timescales.

The third layer is representation and advocacy. Energy UK is the trade body representing suppliers, while consumer bodies, Citizens Advice in England and Wales, Consumer Scotland and the Consumer Council in Northern Ireland, represent households. The energy consumer bodies page explains who does what. For a household trying to work out who is responsible for what, the Energy Ombudsman's guidance is a useful starting point: it directs people to the Energy Networks Association website to find their network provider⁷, which is often the first step in separating a supplier problem from a network problem.

Suppliers and how they affect your energy independence

A supplier is, by definition, a dependency. The market was designed with suppliers as the primary interface between energy consumers and the energy system¹⁴, which means a household that buys all its energy on a tariff is dependent on that supplier's pricing, its solvency, its service and, ultimately, on the wholesale market and the gas that still generates 33.3 per cent of electricity from Major Power Producers². The price cap limits what that dependence costs, but it does not remove it.

The direction of travel, though, is towards households having more of their own. Ofgem's research found 9 per cent of consumers very likely to get an electric vehicle in the next five years²⁹, and suppliers are building products around that shift. Octopus Energy has announced its Nook range of home batteries, scheduled to become available to its customers in the UK from 2027³⁶. Time-of-use tariffs reward households that can shift consumption out of peak hours, which is exactly what a battery, an EV or solar panels enable.

The honest picture is layered. A household with solar panels and a battery still needs a supplier for import, for export payments and for the grid connection that backs it all up. But the balance of power shifts: less energy bought means less exposure to the cap, to wholesale swings and to supplier failure, and more of the household's energy position sits under its own roof. The energy suppliers and energy independence page develops that argument in full. The supplier relationship is not going away, but its size is becoming something a household can choose.