When checking tariffs and changing energy suppliers it is not just a case of getting the cheapest tariff (the price of electricity or gas) available, but also one that suits your household situation.  
To find out the best value tariffs you need to know how much gas or electricity you have used (generally in a year).  This will be on a statement from your supplier, along with the tariff charged.  You can request copies of statements from you supplier. 

Before beginning to check tariffs you will require the following information:
·        Name of your current supplier and tariff
·        Tariff rated from your latest bill.  These should include standing charge or number and price of initial units for both fuels
·        Annual energy used (consumption) for both fuels.

Doing it Online
To make it easier, energy comparison websites give a number of options for entering in your current energy use.  Most people will put in their monthly payments, but this will only give a rough guide.  Ideally actual meter reading (not estimates) for a complete year should be used.  Better still, an average over several whole years to minimise the costs of particularly cold weather. Note:  Last year gas use was 20% higher due to the longer heating season and extended periods of especially cold weather.

It is no longer necessary to pay off one account before transferring. Your account balance (credit or debit) should be transferred to the new provider.     

Use the price checking websites to find the best online tariff for you
The more accurate your usage information, the more accurate the forecast will be by online sites.  This is because the cost is a balance between standing charges and unit prices.  Low energy consumers benefit more from lower standing charges.  The prices shown will usually not include all discounts.

The list below shows all Ofgem, Britain’s energy regulator, approved price checking websites. They should all produce similar results.


Not all the offers will be displayed, as the companies can choose which offers they make available for online switching.  Often things like needing to submit readings online are not that clear.

Switching
The switch can be done through the website but it is best to phone the energy company for any offers which look interesting.  Things like standing orders should be easy to transfer but try to agree how much the payment will be.  Make sure the direct debit payments are high enough.  It is tempting to agree to a smaller payment, which looks like money is being saved, only to receive a large bill at the end of the year.

Doing it by telephone
If you do not have a computer at home here are some of the best comparison sites which give you the information to switch over the telephone.  Don't assume dual fuel is always cheapest.  Check whether getting separate gas and electricity can undercut it.

                    British Gas/Scottish Gas                  New and existing customers: 0800 048 0202
                    Co-operative Energy                         New and existing customers: 0800 954 0693
                    Ebico                                                       Existing customers: 0800 096 6344
                                                                                      New customers: 0800 458 7689 and 01993 608404
                    Ecotricity                                                New and existing customers: 0800 0302 302
                    EDF Energy                                            Existing customers: 0800 096 9000
                                                                                      New customers: 0800 056 5927
                    Eon                                                          New customers to Eon: 0345 301 4905
                    First Utility                                            New and existing customers: 01926 320 700
                    Good Energy                                        Existing customers: 0845 601 1410
                                                                                      New customers: 0845 456 1640
                    Green Energy UK                                 Existing customers: 0800 783 8851
                                                                                      New customers: 0800 954 0675
                    Npower                                                  New customers: 0800 073 3000
                    Ovo                                                          New and existing customers: 0800 5999 440
                    Scottish Power                                    New and existing customers (online): 0845 270 6543
                                                                                      New and existing customers (domestic): 0845 270 0700
                    SSE (includes SWalec,                        New customers: 0800 0482412
                    Atlantic and Scottish Hydro)          Existing customers: 08450260658
                    Spark Energy                                        New and existing customers: 0845 869 4002
                    The Utility Warehouse                      Existing customers: 0844 815 7777
                                                                                      New customers: 0800 131 3000