The Energy Switch Guarantee will see switches cut to just 21 days – down from the four to six weeks it would normally take.
There's also a cooling off period, where you can change your mind within 14 days to stay with your current provider.
Other benefits include the new and old energy company working together to arrange the switch and sort out billing. Though it'll take a maximum of six weeks for your final bill to be sent out under the guarantee, any money you are owed will now be paid within two weeks of receiving it.
What companies are using the energy switch guarantee?
At launch, not all companies have signed up to the guarantee, and more will hopefully join. Those involved include British Gas, EDF, E.ON, First Utility, Flow, npower, Octopus Energy, Sainsbury's Energy and So Energy.
You'll be able to see who is involved by looking for the "energy switch guarantee" logo.
It's not a government scheme, instead it's a voluntary guarantee set up by energy companies. You can read more about it on the Energy Switch Guarantee website.
Don't let hot weather make you think energy switching can wait
Yes, you'll be using less – if any – heating over the summer, and if you're out and about you will probably use less electricity too.
But there are still savings to be made on the price you pay, and if you switch now, you'll already be paying less when temperatures start to drop and the days get shorter
How to find cheaper energy
Research by the energy regulator Ofgem showed the average savings for a household who haven't switched could be as much as £300.
To make the biggest savings you need to compare the different prices available. This is actually a lot easier than it might at first seem. You'll need copies of your bills from the last year. Enter the information required into the comparison site and you'll be presented with different options.
A fixed energy deal is often cheaper than a variable tariff which can go up and down – but remember, at the end of the fix you'll need to compare – and maybe switch – again.
If you are already on a fixed-tariff, watch out for exit penalties which might make it better to wait until the last month of your contract before moving supplier.
More ways to save on energy
Getting electricity and gas from the same supplier is called "dual-fuel" and is usually cheaper.
When you switch, some providers and comparison sites will offer you cashback, giving you back even more.
You can also use less – something that can make a big difference in the summer if you're water is billed through a meter.
This article is provided by the Money Advice Service.