Energy group SSE says it will increase tariffs by 9% on average in a move impacting around 5 million electricity customers and 3.4 million gas customers.
SSE will introduce the bill hike on October 15 and said it comes in response to energy price increases in wholesale markets, as well as rising costs of using the National Grid network.
The UK's second largest energy firm, formerly known as Scottish & Southern Energy, said it will cap bills following the October price rise until at least the second half of 2013.
SSE said the 9% rise, which applies across gas and electricity, will add another £8.53 a month on to the typical monthly direct debit, dual fuel customer - taking the average annual bill to £1,274. The group committed in January to keeping household bills on hold until October.
Ian Marchant, SSE chief executive, said: "Unfortunately, the increases in costs that we have seen since making this pledge can no longer be absorbed and mean that we are unable to keep prices at their current levels beyond this autumn.
"An increase in our prices has therefore, regrettably, become unavoidable."
SSE, which trades as Southern Electric, Swalec and Scottish Hydro, said it had seen a 14% increase year-on-year in the average price in the wholesale market to secure gas for the coming winter.
The group also announced changes to simplify bills by introducing a new fixed standard charge of £100 per year per fuel and a single unit rate for energy used.
It will offer fixed discounts off this price, which will see direct debit customers pay £40 less a year for each fuel, while prompt quarterly bill payers will get a £20 discount per fuel and those choosing paperless billing will get an extra £6 a year per fuel.
The group said it would ensure around 400,000 low-usage customers can remain on a no standard charge tariff if they wish, otherwise they could see their bills rise as a result of the changes.
10 of the biggest consumer rip-offs
Energy firm confirms price hike
Using a mobile phone to make and receive calls, send texts and browse the web while abroad can be extremely costly – especially if you are travelling outside the European Union (EU), where calls can cost up to 10 times as much as at home.
To avoid high charges, Carphone Warehouse suggests tourists ensure a data cap is in place, use applications to check data usage, turn off 'data roaming', avoid data-intensive applications such as Google Maps and YouTube and use wi-fi spots to update social networking sites.
Payment Protection Insurance (PPI) is supposed to help people to continue meeting their loan, mortgage or credit card repayments if they fall ill or lose their jobs. However, policies are often over-priced, riddled with exclusions and sold to people who could not make a claim if they needed to.
At one point, sale of this cover - which was often included automatically in loan repayments - was estimated to boost the banks' profits by up to £5 billion a year.
Now, though, consumers who were mis-sold PPI can fight back by complaining to the bank or lender concerned and taking their case to the Financial Ombudsman Service (08000 234567) should the response prove unsatisfactory.
It could be you, but let's face it, it probably won't be. In fact, buying a ticket for the Lotto only gives you a 1 in 13.9 million chance of winning the jackpot.
With odds like that, you would almost certainly be better off hanging on to your cash and saving it in a high-interest account.
No-frills airlines such as EasyJet may promote rock-bottom prices on their websites. But the overall fare you pay can be surprisingly high once extras such as luggage and credit card payment fees have been added - a process known as drip pricing.
Taking one piece of hold baggage on a return EasyJet flight, for example, adds close to £20 to the cost of your flight, while paying by credit card increases the price by a further £10.
It may therefore be worth comparing the total cost with that of a flight with a standard airline such as British Airways.
Cash advances, which include cash withdrawals, are generally charged at a much higher rate of interest than standard purchases.
While the average credit card interest rate is around 17%, a typical cash withdrawal of £500, for example, is charged at more than 26%.
What's more, as the interest accrues from the date of the transaction, rather than the next payment date, costs will mount up even if you clear your balance in full with your next payment.
Supermarkets such as Tesco and Asda often run promotions under which you can, for example, get three products for the price of two.
However, it is only worth taking advantage of these deals if you will actually use the products. Otherwise, you are simply buying for the sake of it, which is a waste of your hard-earned cash.
Buy a train ticket at the station on the day of travel and the price is likely to give you a shock - especially if you are travelling a long distance at a busy time of day.
However, you can cut the cost of train travel by 50% or more by going online and making the purchase beforehand - especially if you book 12 weeks in advance, which is when the cheapest tickets are on sale.
Other ways to reduce the price you pay include avoiding peak times and taking advantage of so-called carnet tickets, which allow you to buy, for example, 12 journeys for the price of 10.
Most High Street banks offer packaged accounts that come with monthly fees ranging from £6.50 up to as much as £40, with a typical account charging about £15 per month.
Various benefits, such as travel insurance and mobile phone insurance, are offered in return for this fee. But whether or not it is worth paying for them depends on your individual circumstances.