Who Are the Big Six Energy Suppliers in 2026? UK Market Guide for Homes & Businesses Quick answer
The UK’s “Big Six”
The traditional Big Six were:
British Gas
EDF Energy
E.ON
npower
ScottishPower
SSE
In recent years, the market changed after supplier collapses, mergers and customer book transfers. A more modern Big Six is often described as:
British Gas
EDF Energy
E.ON Next
Octopus Energy
OVO Energy
ScottishPower
However, this is changing again in 2026. E.ON announced a planned acquisition of OVO’s UK energy retail business in May 2026, and the Competition and Markets Authority opened an invitation to comment on the anticipated acquisition in July 2026.
For business energy customers, the most important point is not whether a supplier is in the Big Six. It is whether the supplier offers the right contract, unit rates, standing charges, service, billing support and terms for your business.
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Use this guide if you are comparing:
British Gas Business
EDF Business Energy
E.ON Next Business
Octopus Energy for Business
ScottishPower Business
OVO Energy Business
SSE Energy Solutions
TotalEnergies Gas & Power
Crown Gas & Power
United Gas & Power
Opus Energy
Yu Energy
business energy brokers
smaller business energy suppliers
Business Energy Bill Calculator UK Estimate your monthly and annual business electricity and gas costs using your kWh usage, unit rates, standing charges and VAT.
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This calculator is an estimate only. Actual business energy bills vary by supplier, meter type, region, contract, usage, VAT treatment, standing charges, Climate Change Levy, pass-through charges and renewal terms.
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Authored by: Ally Cox (Business Technology & B2B Services Specialist 10+ Years’ Experience)
Reviewed by: James Ward (Telecoms Specialist, 12+ Years Experience)
Last Updated: August 2026
Contents
The Big Six Energy Suppliers
The State of the UK Energy Market
Risks of a Dominated Market
Barriers to Switching Energy Providers
Recent Collapses of UK Energy Suppliers
Key Takeaways
The phrase “Big Six” originally referred to British Gas, EDF, E.ON, npower, ScottishPower and SSE.
The modern large-supplier group is often described as British Gas, EDF, E.ON Next, Octopus Energy, OVO and ScottishPower.
E.ON announced a planned acquisition of OVO in May 2026, subject to regulatory approvals.
The CMA opened an invitation to comment on the anticipated E.ON/OVO acquisition in July 2026.
Ofgem’s retail market report says six large companies dominate the domestic market with 91% market share.
For business energy, the biggest supplier is not always the cheapest or best fit.
Businesses should compare unit rates, standing charges, contract length, renewal terms, broker commission and total annual cost.
Smaller suppliers can sometimes offer competitive business energy deals.
If a business energy supplier fails, Ofgem can appoint a new supplier, but business customer credit balances are not protected in the same way as domestic customer balances.
Always check contract end dates before switching, because most business suppliers will not let you switch before the end of a fixed contract.
The State of the UK Energy Market: February 2026 As of 2025, the current “Big Six” energy suppliers in the UK are:
British Gas EDF Energy E.ON Next Octopus Energy OVO Energy ScottishPower
These suppliers now serve the majority of UK customers following market restructuring between 2020 and 2023.
What Happened to the Old Big Six? The original group (British Gas, EDF, E.ON, ScottishPower, SSE and npower) has changed:
npower → Was absorbed by E.ON
SSE → a domestic customer base acquired by OVO
(This reshuffle is why OVO and Octopus now sit in the “Big Six.”)
What happened to the old Big Six? The original Big Six changed because of mergers, acquisitions and customer transfers.
Original Big Six supplier
British Gas
Still one of the major suppliers
EDF Energy
Still one of the major suppliers
E.ON
Became E.ON Next for domestic and SME customers
npower
ScottishPower
Still one of the major suppliers
SSE
Domestic customer base was acquired by OVO
Who are the Big Six energy suppliers in 2026?
Supplier Why it is included
British Gas
One of the UK’s largest and best-known energy suppliers
EDF Energy
Major electricity and gas supplier with large domestic and business presence
E.ON Next
Large supplier following E.ON’s acquisition of npower customers
Octopus Energy
Major challenger supplier that became one of the UK’s
largest providers
OVO Energy
Large supplier after acquiring SSE’s domestic customer base
ScottishPower
Long-standing major supplier and part of the original Big Six
Why the Big Six changed The UK energy market changed for several reasons:
supplier collapses during the energy crisis
wholesale price volatility
tighter financial resilience requirements
acquisitions and customer transfers
growth of challenger suppliers
increased focus on smart meters and digital billing
growing demand for renewable tariffs
changing customer expectations
consolidation among larger providers
Ofgem says six large companies dominate the domestic market with a 91% market share, and that Octopus is now the largest electricity supplier and second-largest gas supplier in Great Britain.
Are the Big Six Still Dominating the UK Market? Yes,but the landscape is stabilising after years of volatilit and right noW:
Over 85% of UK energy customers are with the top 10 suppliers
Smart meters and digital billing are now standard
Businesses prioritise renewable and net-zero aligned suppliers
For deeper market insight, see Ofgem’s latest supply market indicators.
E.ON and OVO: what businesses need to know In May 2026, E.ON announced that it planned to acquire OVO’s UK energy retail business.
OVO also confirmed that it had agreed the sale of its UK energy retail business to E.ON, subject to regulatory approvals.
In July 2026, the CMA opened an invitation to comment on the anticipated acquisition.
This matters because OVO is often included in the modern Big Six list.
If the acquisition is completed, the UK’s largest supplier landscape may change again.
For now, businesses should:
check current supplier status before publishing final wording
avoid saying the Big Six list is permanent
compare suppliers based on business quotes rather than brand size
update this page if the E.ON/OVO deal receives approval
avoid relying on old “Big Six” definitions in business energy content
Big Six suppliers vs smaller suppliers Large suppliers and smaller suppliers can both be suitable for businesses.
The best choice depends on your usage, meter type, sector and contract needs.
Option
Potential advantages
Big Six / large supplier
Scale, brand recognition, broad service coverage, business support
Not always cheapest, service can vary, contracts may feel less flexible
Smaller supplier
Competitive pricing, niche support, flexible service, more personal account management
Supplier stability, billing quality and business support should be checked
Energy broker
Can compare several suppliers and contract options
Ask how commission is paid and included
Specialist business supplier
Useful for SMEs, multi-site firms or complex meters
Check contract terms and support carefully
Are Big Six suppliers cheaper for businesses? Not always.
Big Six suppliers can be competitive, but business energy pricing is not universal.
Your quote depends on:
postcode
electricity usage
gas usage
meter type
contract end date
business type
credit profile
contract length
standing charge
unit rate
market timing
broker commission
payment terms
whether you need one site or multiple sites
Should businesses use a Big Six supplier? A Big Six supplier will be suitable if your business wants:
a recognised supplier
business gas and electricity options
online account tools
larger customer service infrastructure
multi-site options
fixed contracts
green tariff options
smart meter support
established billing systems
broad market experience
Business energy contracts: what to compare Before choosing any supplier, compare:
electricity unit rate
gas unit rate
daily standing charge
contract length
total annual cost
renewal window
out-of-contract rates
deemed rates
broker commission
payment terms
direct debit rules
smart meter support
half-hourly meter support
customer service
complaint handling
green tariff evidence
VAT and Climate Change Levy treatment
termination terms
whether the supplier supports your business type
What happens if an energy supplier goes bust? Ofgem has a process for appointing a new supplier if an energy supplier fails.
For business customers, Ofgem says the new contract will last for as long as you want it to.
However, business customers should be aware that the Safety Net does not cover business customer credit balances in the same way as domestic customer credit balances. Business customers may need to apply to the failed supplier’s administrators, and Ofgem says it will try to appoint a new supplier to cover outstanding credit, but this is not guaranteed.
This means businesses should consider supplier stability, not just price.
What Are the Risks of a Dominated Market? A market led by a few major firms presents several risks:
🔻 Less price competition
With fewer players, the pressure to offer competitive rates reduces – potentially leading to higher energy bills .
🌀 Reduced transparency
Large suppliers may trade wholesale energy internally, which can affect price fairness and public accountability.
💥 Greater shock impact
When major suppliers make pricing or operational changes, millions of customers are affected at once .
For economic context, see the UK Energy Research Centre’s market insights:
What Stops People Switching Energy Providers? Despite better switching tech and awareness, common myths still hold businesses back :
🚫 “Switching means new cables or meters” – False. Your infrastructure stays the same.
🚫 “I rent my property, so I can’t switch” – Not true. If you pay the bills, you can choose your supplier.
🚫 “It takes weeks to switch” – The average switch takes just 2–5 working days in 2025.
📢 TIP: Use your renewal window to compare deals and avoid being rolled into an expensive standard tariff, and For switching help and comparison tools, see Citizens Advice :
Should You Consider Smaller Suppliers? While the Big Six dominate, lots of smaller suppliers still play a vital role in the market.
✅ Advantages:
Personalised customer service
Innovative tariffs (like tme-of-use, a lot are EV-friendly)
Flexible contract options for SMEs
❌ Watch out for:
Financial resilience (check credit ratings and Ofgem approval)
Limited business support or account management features
Switching is simple, safe, and can lead to big savings.
FAQs for the Big Six Energy Suppliers Who are the Big Six energy suppliers in 2026?
The modern Big Six are often described as British Gas, EDF, E.ON Next, Octopus Energy, OVO Energy and ScottishPower. However, this may change because E.ON announced a planned acquisition of OVO in 2026.
Who were the original Big Six energy suppliers?
The original Big Six were British Gas, EDF, E.ON, npower, ScottishPower and SSE.
What happened to npower?
npower was absorbed into E.ON, which is why it is no longer usually listed as one of the modern Big Six suppliers.
What happened to SSE Energy?
SSE’s domestic customer base was acquired by OVO, which helped OVO become one of the UK’s largest suppliers.
Is OVO still one of the Big Six?
OVO is often included in the modern Big Six list, but E.ON announced plans to acquire OVO’s UK energy retail business in May 2026. The CMA opened an invitation to comment on the anticipated acquisition in July 2026, so the position may change.
Is Octopus one of the Big Six?
Yes, Octopus is widely treated as one of the large modern UK energy suppliers. Ofgem’s retail market report says Octopus is the largest electricity supplier and second-largest gas supplier in Great Britain.
Are the Big Six always the cheapest?
No. Big Six suppliers are not always the cheapest for business energy. Pricing depends on usage, postcode, meter type, contract length, standing charge, unit rate and market timing.
Should businesses use a Big Six supplier?
A Big Six supplier can be a good option for stability, service coverage and business support, but businesses should still compare smaller suppliers, brokers and specialist business energy providers.
Are smaller energy suppliers safe?
Smaller suppliers can be suitable, but businesses should check contract terms, billing quality, reviews, support and supplier stability before signing.
What happens if my business energy supplier fails?
Ofgem can appoint a new supplier. For business customers, the new contract will last for as long as the business wants it to, but business credit balances are not protected in the same way as domestic customer balances.
Can businesses switch energy suppliers easily?
Businesses can usually switch when their contract allows. Most fixed business energy contracts prevent switching before the contract ends, so check your renewal window and termination terms.
Do I need new meters or cables to switch supplier?
Usually no. Switching supplier normally changes who bills you for energy, not the physical wires, pipes or meter. Some smart meter or metering changes may happen separately depending on setup.
Does the energy price cap apply to business energy?
No, the domestic energy price cap does not work in the same way for business energy contracts. Businesses should compare contract rates carefully.
What should businesses compare before choosing an energy supplier?
Compare unit rates, standing charges, contract length, total annual cost, renewal terms, customer service, broker commission, green tariff evidence and supplier suitability for your meter type.
Is a broker better than going direct?
A broker can help compare multiple suppliers, but you should ask how they are paid and whether commission is included. Going direct may work if you already know which supplier you want.
Related Business Energy Guides Compare & Switching Guides Sector-Specific Energy Guides Tariffs, Pricing & Market Explained Meters, Technical & Admin Guides Green & Renewable Energy Options Major UK Business Energy Suppliers Cost Reduction & Strategy Market & Government Updates Hi, I’m Ally Cox , a senior copywriter and blogger at CompareYourBusinessCosts.co.uk, the UK’s trusted platform for comparing business services.over a decade of experience in the B2B sector, I specialise in simplifying complex topics like leased lines, VoIP, business energy, HR and payroll solutions, accounting software, and EPOS systems .HR, copywriting, and business operations- from clocking-in systems to card machines and office technology .informed, confident decisions when choosing products and services that improve efficiency and save money.
