Energy price comparison sites have been told to shape up if they want their services to be accredited by the regulator.
From the end of March they must ensure they include at least 10 tariffs for consumers to compare and they must be upfront about which deals will earn them commission from energy companies.
They will also have to make it clear to customers that they are able to switch energy firms by contacting them directly.
As part of its new code of confidence, accredited comparison sites will also be banned from displaying a 'default partial view' of summary deals from suppliers that pay them the most commission.
This means the sites will have to display all tariffs available, unless the customer actively chooses to see a summary.
The websites must also put an end to the use of confusing language and ensure they explain tariffs and customer choices clearly to their users. This wording must be signed-off by Ofgem.
Comparison sites that do not comply with the code will not be accredited by the regulator and risk being perceived by consumers as less trustworthy. At present, collective switching schemes are not part of the code but Ofgem says it could broaden the scope of the code to such schemes in future.
Around 40% of energy customers used a comparison site before switching suppliers last year.
Save £200 by switching
Rachel Fletcher, Ofgem senior partner, said: "Our market reforms have made it easier for consumers to pick out better deals and switch suppliers. There has never been a better time to switch – consumers can make savings of around £200 by switching. Comparison sites are a great place to start energy shopping, but customers need to feel confident that the sites are providing information they can trust."
Mark Todd, managing director of energy comparison site Energy Helpline, added: "We support the toughening up of rules and are confident we already meet these standards.
"With the energy market increasingly under the spotlight, it is good to see Ofgem toughening up the confidence code today, setting a gold-plated standard, the toughest of any comparison industry in the world."
A spokesman for uSwitch.com, said: “The new code is fully in line with our ongoing plans to develop our service so consumers can continue to compare tariffs in a simple, transparent, fair, independent and unbiased way.
“We have been calling for some time for all price comparison websites and collective switching schemes to be Confidence Code compliant, so strongly welcome Ofgem's decision to look at extending its scheme.”