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How to switch energy supplier

Getting an idea of the energy tariffs' prices available will help you understand if there's a deal worth switching to for you.
Marianne Calnan
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Avoid paying more than you need to for gas and electricity. Use our expert advice to switch energy firm with confidence, and choose a deal that’s right for your household.

While savings on your energy bills are limited at the moment, it's still worth keeping an eye on how your tariff compares.

You can still take a look at what's available on the energy market in your area using Which? Switch:

Read on to find out more about the switching process, including what you'll need, what information to look out for and what to do if you encounter an issue.

1. What you need to switch energy supplier

The more detailed information you can provide when you're getting a quote for a new gas and electricity tariff, the more accurate it will be. Make sure you have the following information to hand:

Your full address

Prices vary by region, and some energy deals are only available in certain areas, so using your full address will make sure that the quotes you get are applicable to your home. 

The name of your current gas and electricity supplier and tariff

You’ll need to provide these so that any savings estimates are based on the deal you’re on currently.

If you don’t provide the name of your current tariff, a price comparison website will often assume you’re on your supplier's default or out-of-contract tariff.  This may be more expensive than your current deal, so you risk getting an over-inflated savings figure.

Without the name of your current energy supplier, the default used may be the company that historically supplied your area. As with assumptions about your tariff, there’s a risk that this will make your savings look bigger than the reality.

To find out the name of your energy tariff, check your latest bill, look at your online account or contact your supplier.

How much gas and electricity you use

To get an accurate quote for gas and electricity costs, you'll need to state your energy use, usually in kilowatt hours (kWh), for the past year.

Your latest bill or online account should tell you how much you've used in the past month. Look for your annual energy statement or summary for your use over a year.

If you don’t know how much energy you will use – for example, if you've just moved into a new home – you can estimate instead. Price comparison websites, energy firms and autoswitching services will often ask a few questions to estimate what you use, for example:

  • The number of people living in your home
  • The type of property
  • The number of bedrooms.

Find out more about estimated energy-use figures.

But bear in mind that calculating your payments in this way will be less accurate than using your actual energy use. So a few months into your contract, your payments could change to reflect how much gas and electricity you're actually using in practice.

Your payment details

To pay by direct debit, you'll need to provide your bank details upfront. Sometimes credit card details are allowed.

2. Compare gas and electricity prices

With all these details to hand, you’re ready to compare energy prices. Below are some of the ways you can do that.

Price comparison websites show you a range of deals so you can compare costs. Our free and independent service, Which? Switch, is one of these. It shows all available energy deals on the market, regardless of whether it can switch you to them, so you’ll know whether the deal you pick is really the cheapest.

Some price comparison websites have a phone switching service as well.

Contacting an energy company directly is another way to compare energy firms and tariffs. Consider that the energy company will only be able to tell you about its own deals, and it won’t be able to switch you to those that are exclusive arrangements with third parties (such as price comparison websites). 

Autoswitching services are the newer kids on the block and there's a growing number of them.

Like price comparison websites, they compare prices based on your preferences. But they do the legwork for you, switching you (with your permission) to what they calculate to be the best deal for you, then continually checking prices to keep you on the best deal. Some won’t switch you to suppliers whose service they consider to be poor.

Regardless of the switching method you use, there are various types of tariff to choose from, depending on what's important to you. Here are some of the most common ones:

  • Fixed tariff – the amount you pay per unit of gas or electricity is fixed for the term of your deal, often one or two years.
  • Variable tariff – the amount you pay per unit of gas and electricity will change whenever your energy company raises or lowers its prices. It must give you 30 days’ notice when it’s doing this, though.
  • Dual-fuel tariff – includes both gas and electricity, and is handy if you want to buy both fuels from one supplier.
  • Paperless tariff – also called online-only. You won’t get bills through the post, and will need to manage at least some of your account online. Some suppliers charge less for these, but not all.
  • Time-of-use tariff – these charge different rates for electricity depending on the time of day, or day of the week. Economy 7 and 10 tariffs are longstanding examples. Smart meters’ half-hourly readings enable companies to offer more of these.

Find out more about different types of tariffs and how to get the best energy deal.

3. Energy tariffs: what to check before you switch

Once you’ve chosen your energy company and tariff, check the following to avoid any surprises later:

  • Does your tariff have exit fees? Some firms charge as much as £50 per fuel if you want to leave before the end of your contract. Exit fees only apply to fixed deals, and cannot be charged in the last 49 days of your tariff.
  • How much will your new deal cost per month? Check how this compares with your current deal, so there are no surprises to your bank account.
  • Is your direct debit fixed or variable? Fixed direct debit payments are the same each month, to balance out the cost of your energy during the year. Some companies have different fixed payments for summer and winter. Variable direct debit payments will change each month to match what you use.
  • How will you receive your bills? Remember to check your online account or email if you won’t be getting them through the post.
  • Does your tariff require a smart meter? Some tariffs are only available to customers with smart meters, or if you agree to have one fitted.
  • Is there an upfront payment? Some tariffs require one month's payment (or even two, in the case of one supplier) before they start supplying your gas and electricity. Some prepayment deals require a security deposit. Both of these can make the initial costs of switching higher than expected.

4. How long does it take to switch energy supplier?

It takes up to 21 days to switch to a different energy firm, but will typically take 17 days, according to energy regulator Ofgem.

That’s not including the 14-day cooling-off period the supplier must leave in case you want to change your mind before it begins the switch.

If you’re keen for a quicker switch you can choose a company signed up to the Energy Switch Guarantee – a set of voluntary standards launched by the energy industry in 2016. Sine 2019 new rules require energy companies to compensate switchers if there's a problem. See below for more on this. 

Companies signed up to the Energy Switch Guarantee commit to switching your energy supply within 21 days (including the cooling-off period).

These are: British Gas, Bulb, EDF Energy, Eon, ESB Energy, Octopus Energy, Outfox the Market, Shell Energy, So Energy and SSE (correct April 2022).

They also guarantee to contact your old energy supplier to tell it you’re leaving, work with it to make sure you’re not charged twice, and take responsibility if there are any problems. Once you've switched, they promise to send you a final bill within six weeks, and refund you any money owed within 14 days. Find out more about the Energy Switch Guarantee.

5. Will I get compensation if I have a problem switching?

If something goes wrong when you switch energy supplier, you may be eligible for compensation.

Ofgem rules state that energy firms must pay customers £30 if:

  • You are switched without your permission or by mistake
  • Your switch is not completed within 15 working days (after the 14-day cooling-off period has elapsed)
  • Your supplier fails to send you your final bill within six weeks of your switch
  • Your credit balance is not refunded within 10 working days of your supplier sending your final bill.

Different rules apply to suppliers that have gone out of business.

The compensation is automatic, although you may need to tell your energy supplier about the problem. 

6. How to switch energy supplier as a tenant

If you rent your home, you can still usually switch your energy supplier to get a cheaper deal. If you pay your energy company directly for your gas and electricity, then you can choose your energy supplier according to consumer protection law.

But if your landlord pays the energy company direct, they can choose the energy supplier. You might be in this situation if:

  • Your energy costs are included in your rent
  • Your landlord pays your energy supplier and reclaims the money from you
  • Your landlord has taken responsibility for energy bills between tenancies.

Your tenancy agreement should state whether you or your landlord is responsible for paying the gas and electricity bills. If your landlord pays the energy bills, you can ask them to change your supplier but they don’t have to.

Your tenancy agreement might include a ‘default’ or preferred energy supplier that your landlord or estate agent has set up. You can ask to renegotiate this clause in your contract. Even if you can't change it, you're entitled to switch company as long as you pay the bills directly. You should inform your landlord or letting agent, though, and there may be a clause that requires this.

There may also be a clause stating that you must return the account to the original energy supplier when you move out.

If you've just begun a new tenancy or haven’t switched energy supplier or tariff in a while, it’s likely you’re on the energy firm’s standard default or out-of-contract tariff. These are rarely the cheapest deals, so it’s worth comparing energy prices to see what you could save.

Which? Switch, our independent energy comparison site, can help you to find the best deal for you as a tenant, regardless of how long you’ll be renting for.

Select the length of your tenancy to compare energy prices based on how long you know you’ll be in your home, taking any exit fees into account.

If you have a prepayment meter and rent your home, you should still be able to switch. Find out whether a prepayment energy meter is right for you.