In the UK energy market, the term Big Six refers to the largest energy suppliers that dominate both domestic and business energy contracts. While the makeup of this group has evolved over time, their influence within the energy sector remains significant, especially for businesses navigating complex and often costly agreements.
The Current Big Six Energy Suppliers (2025)
As of 2025, the Big Six energy companies in the UK are:
- Octopus Energy
- British Gas
- E.ON Next
- OVO Energy
- EDF Energy
- ScottishPower
These six suppliers collectively provide energy to over 87% of UK households and a substantial portion of the business sector.
How Has the Big Six Changed?
Historically, the Big Six included British Gas, EDF, E.ON, npower, ScottishPower and SSE. However, the energy crisis of 2021–2022 and a wave of mergers and acquisitions reshaped the landscape:
- OVO Energy acquired SSE’s customer base in 2019.
- E.ON Next absorbed npower’s customers in 2021.
- Octopus Energy rapidly expanded, overtaking British Gas in 2023 to become the UK’s largest electricity supplier.
While the names have changed, the energy market remains highly concentrated, a reality which continues to pose challenges for businesses.
Why Does the Big Six Matter for Businesses?
At Business Energy Claims, we’ve seen first-hand how market dominance can lead to:
- Uncompetitive tariffs
- Limited switching options
- Hidden broker commissions
- Long-term contracts with inflated rates
With fewer suppliers controlling the majority of the market, businesses often find themselves locked into expensive deals, sometimes without knowing they have been mis-sold.
The Risks of a Dominated Market
When just a handful of companies control the energy supply, competition suffers. This can result in:
- Higher prices: Suppliers may not feel pressure to offer competitive rates.
- Opaque practices: Hidden commissions and complex contracts are harder to challenge.
- Reduced trust: Many businesses are hesitant to switch, fearing instability among smaller providers.
In fact, more than 25 smaller energy firms have collapsed in recent years, reinforcing the dominance of the Big Six and making it harder for businesses to find better deals.
What Can Businesses Do?
Even within a concentrated market, businesses have options:
- Review your current contract: Understand your rates, terms, and whether a broker was involved.
- Compare suppliers: Don’t assume the Big Six offer the best value, smaller providers may offer better service and pricing.
- Seek legal advice: If you suspect mis-selling or hidden fees, you may be entitled to compensation.
At Business Energy Claims, we help businesses uncover hidden commissions and challenge unfair contracts. With an estimated 2 million UK businesses potentially affected, now is the time to act.
Think you have a mis-sold energy contract?
Contact our expert team today to find out if you’re eligible for compensation.