Ofgem's decision to remove price controls was based on their assessment that competition was developing well at that time and that the Competition Act 1998, being effective since March 2000, would deter companies from the abuse of market power, and provide Ofgem with sufficient power to tackle any abuse.

In 2006, Ofgem required the industry to set up and fund the Energy Supply Ombudsman in response to concerns over the handling of customer complaints.

[19] Ofgem's Energy Supply Probe, published in 2008 after increases in world fuel prices led to the doubling of the energy bill for a typical household, found that the market was still dominated by the "Big Six" suppliers: more than 70% of customers were still with their former monopoly suppliers, and new entrants had captured less than 0.3% of the market.

Ofgem implemented a number of measures which improved the information provided to customers and made it easier for them to switch suppliers.

The Big Six were obliged to separate their accounting for the supply and generation businesses, and Ofgem noted concerns over market abuses and unfair pricing.

This will help rebuild consumer trust and confidence in the energy market as well as provide the certainty investors have called for," Ofgem CEO Dermot Nolan in announcing the investigation.

[22] In October 2017, Prime Minister Theresa May announced her intention to introduce a cap on standard variable tariffs for energy customers, to be designed and implemented by Ofgem.

[27][29] In response, Ofgem accepted that its previous financial resilience regime was not sufficiently robust, and had contributed to some of the supplier failures since August 2021.

[30] In September 2018, the Guardian published a report claiming that two Ofgem experts had been independently threatened with criminal sanctions if they publicly revealed information.

Ofgem allegedly invoked section 105 of the Utilities Act 2000, designed to protect national security, relating to concerns about smart meters and Renewable Heat Incentive projects.

[33][34][35] Notable payments into the scheme include: £12.5M from PayPoint for breaking the 1998 Competition Act;[36] £8.9M from OVO Energy for overcharging customers;[37] £4.5M from Hornsea Wind Farm, £4.5M from Npower and £1.5M from UK Power Networks for failing to remain connected after a lightning strike causing a widespread blackout on 9 August 2019;[38] £2.8M from OVO Energy, £2m from Scottish Power, £1.3M from British Gas, £1.2M from Shell Energy, £1M from SSE plc and amounts from £7k to £713k from 13 other energy suppliers for overcharging between 2013 and 2020;[39] £1.5M from Utility Warehouse for treating customers unfairly and increasing their financial distress;[40] and £1M from SSE for sending inaccurate customer statements.