A new cashback offer has made Sainsbury's Energy the cheapest supplier, based on average consumption.

The deal gives you £50 off its Online S@ver Version 6 deal, which is provided by EDF Energy but branded Sainsbury's.

It costs a typical household £854 a year after the discount, which price comparison site Energyhelpline.com says puts it at the top of the best-buys.

While the deal is the cheapest on average, the energy market is complicated so what you spend depends on where you live and how much gas and electricity you use. For many, this could therefore be pricey (see the Cheap Gas & Electricity guide).

Sainsbury's offer

To get the cashback, which will be applied to your first bill, you must apply by the end of this month.

The tariff is variable, so can rise or fall in price, but is guaranteed to stay 2% below EDF's standard tariff until 30 June 2011.

It is available for dual fuel customers (where you take gas and electricity) or electricity only. If you exit before 30 June next year you'll pay up to £50 in fees.

Mark Todd, from Energyhelpline, says cashback incentives have crept into the market over the past year as a new way to attract business.

How to find the best deals

Households can sometimes cut their bills by hundreds by checking the tariffs available on a specialist comparison site, and switching (see the Compare Gas & Electricity and Get Cashback guide).

Those languishing on their supplier's standard tariff or who get bills through the post are almost certainly paying too much.

While the cheapest online deals for typical users are less than £900 a year, those on a standard tariff typically pay around £1,200.

Further reading/Key links

Slash energy costs: Cheap Gas & Electricity
Your rights: Fight Energy Direct Debits
Capped tariff help: Is your Cap/Fix ending soon?
Boiler protection: Boiler Cover