Energy customers are facing a potential "Halloween horror" from rocketing bills - as 12 fixed dual fuel deals are due to expire at the end of October.
Comparison website GoCompare.com said that households on the deals which are set to end stand to see an average annual increase in their bills of £147.95 or 15.2% if they sit tight and allow themselves to be rolled onto their supplier's standard variable tariff.
GoCompare's calculation is based on a household using a medium amount of energy and the average is taken across all the deals which are set to end.
It said that Npower, Co-operative Energy, Scottish Power, Sainsbury's Energy, Extra Energy and First Utility all have dual fuel tariffs that are set to expire on October 31.
The deals will come to an end just as many households up and down the country start to put the heating on as temperatures edge downwards.
Compare energy prices here
Caroline Lloyd, an energy spokeswoman at GoCompare.com, said: "The 12 fixed dual fuel tariffs due to expire on Halloween could result in a substantial price rise for customers on those tariffs."
- Regularly shop around and compare providers. If you have been with the same provider for a long period of time, it is unlikely you are getting the best deal.
- Become more mindful of what is switched on in your home can help reduce your monthly bills. Leaving lights and radiators on when you are not around can add up. Turning off electrical appliances at the mains rather than leaving them on standby will also help bring down electricity costs.
- Use timers. Putting the heating on a timer cuts out the risk of accidentally leaving it on all day. In the evening, you could set the heating to go off before you go to bed, so that it is not needlessly on when you are under the duvet.
- Be water efficient. If you have got a shower that takes hot water straight from your boiler or hot water tank, you may be able to fit a shower head to reduce your hot water usage while still enjoying a proper shower. Some water companies will give these away for free.
- Smart meters show you exactly how much energy you use and how much it will cost. You can use smart meters to ensure you are giving your provider an accurate energy reading, which means your bills should not be under or overestimated.
- Reducing the temperature of your washing machine can help save on electricity.
More on AOL Money:
British Gas price cut 'not enough'
Power bills may rise amid winter capacity fears
Energy firms 'overcharging customers £120'