From today, a new rule states that energy suppliers must provide consumers with at least 30 days notice of impending price risesor changes which could see a significant amount added to their bill.
The ruling was ushered in by industry regulator Ofgem, which has also ordered energy companies to abolish the complex pricing systems.
It is thought the rule will allow customers to decide whether they wish to remain with their current supplier and budget for any price rises.
Ofgem is also consulting on changes that will attempt to break up the monopoly the leading six energy providers have in the electricity market and introduce further industry transparency.
The companies have until June to respond to the regulator's suggestions.
In response to Ofgem's requirement coming into effect, Hannah Mummery, energy expert for Consumer Focus, said: "People clearly need to be given fair warning if prices are going to go up, not told months after the event. This welcome move will help give people the opportunity to budget for higher bills in advance, weigh up their options about whether to switch supplier and shop around."
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