Energy providers must give customers 30 days notice of any price rises under a new rule introduced today.
In what is a major coup for consumers, Ofgem, the industry regulator, has announced that providers will no longer be allowed to wait until after the increase to inform their customers.
Previously companies had 65 working days to tell customers about price hikes after they have been introduced.
Shop around for deals
Mark Todd, director of Energyhelpline.com, says: "The new 30-day notice period will give people time to find better deals, switch suppliers and save money. We estimate if it had been brought in before the last round of rises, which averaged 5.9%, it could have saved the nation's hard-pressed households £146 million by enabling them to switch to avoid the price rises."
Todd says it is "absurd" that providers have been able to announce price rises retrospectively.
He adds: "Imagine going to a supermarket and being charged £90 for groceries and then being told three months later that actually the price was £100 and that they now wanted an extra £10. There would be uproar."
Check out the Moneywise Energy Switcher to see if you could save money on your utility provider
In a further move to promote fairness in the energy market, Ofgem announced plans to increase competition, resulting in better-priced deals for customers.
Andrew Wright, Ofgem's senior partner for markets, says: "Ofgem is currently consulting on its plans to radically overhaul the energy market - through sweeping away complex prices and breaking the stranglehold of the big six energy providers by making them auction up to 20% of their generation output."
Ofgem says at the moment it's difficult for smaller players to get a foothold in the market as they rely on the big six providers to trade with them. Making the bigger players auction some of their power generation to smaller providers through trading platforms will promote competition.
All six of the big energy providers - British Gas, Scottish Power, Scottish and Southern Energy, Npower, E.ON and EDF - have increased their prices in recent months.
How easy is it to change providers?
Switching providers takes between four to six weeks. However, an Ofgem rule is in place, which states once you have been informed of a price rise you can reject the increase, tell your provider you want to leave and start the switching process. This means as long as you tell your provider and begin the switching process within the 30-day period even when this is up you will not be charged the new price.
Read: Five things to consider when choosing an energy supplier
Emma Bush, an energy expert at uSwitch, says: "Make sure there are no barriers in the way which could hold up the switching process. For example, if you have an existing debt with your supplier this can cause delays.
"It's also important to give an accurate meter reading on the day of the switch. You'll receive a letter from your new provider telling you what day the switch will take place. Give an accurate reading to your new and old provider to make sure you are billed correctly."