Energy customers advised to shop around as nine fixed-rate tariffs end

Customers on some fixed-rate British Gas and Sainsbury’s tariffs will see their bills drop when the deals end. Photograph: Matt Cardy/Getty Images

Householders who signed up to one of nine fixed gas and electricity tariffs due to end within days should switch to a better deal, or face an increase of up to £317 on their annual fuel bill.

British Gas, EDF Energy, npower, Sainsbury’s Energy, First Utility and Flow Energy all have tariffs due to expire at the end of the month, at which point customers on these deals will be automatically rolled on to their supplier’s standard tariff. Where the standard tariff is more expensive than the current deal, households will see an average 8.14% or £90 increase to their annual bills if they fail to shop around and switch to a cheaper supplier.

For households in the Norweb region, which includes Manchester, the effect of their fixed tariff coming to an end looks particularly pricey. Customers there who are on the First Utility iSave fixed August 2015 v23 tariff could be hit with a huge £317 (24%) rise when they are switched to the standard tariff.

EDF customers on its popular Blue+ price promise August 2015 tariff will see a typical increase of £105 a year – or 10% – if they do nothing.

However, it is not all bad news: customers on the British Gas Fix & Control August 2015 and Fix & Reward August 2015 tariffs, as well as those on the Sainsbury’s Energy Fix & Reward August 2015 tariff will see their bills drop by an average £58 (4.8%). They have effectively been overpaying on those fixed deals. British Gas customers in particular can get a much cheaper deal by leaving the company.

Caroline Lloyd, energy spokeswoman at Gocompare.com, says: “For a number of years now fixed tariffs have proved popular, due to the fact they have tended to be the most competitively priced deals. Make no mistake – standard tariffs do not represent good value. There are always other tariffs, whether fixed or variable, that will provide better prices.”

Three suppliers, GB Energy, extraenergy and First Utility, offer fixed gas and electricity tariffs that come in at less than £900 a year for an average house. Ovo Energy’s better energy fixed (all online) deal at £918 is the Guardian Money pick at the moment, largely because it has a proven customer service record.

• Households should always check which is the best deal for them. The Guardian offers an impartial switching service. Go to guardianenergycomparison.co.uk or call 0800 634 3874, Mon-Fri 9am-8pm, Sat-Sun 9am-5pm.

• This article was amended on 3 September 2015 to remove a table which contained an error.