Because many savings account providers offer bonus rates on new accounts, savers are being urged by moneysupermarket.com to ensure their bonus rate is fixed.
The price comparison site suggests some providers will offer customers variable bonus rates in an attempt to attract new savers, but rates can fall earlier than expected.
The research shows that the average bonus rate now stands at 1.93 per cent compared 0.71 per cent two years ago, whilst the number of products with bonus rates has increased from two to eight.
Commenting on this news, Kevin Mountford, head of banking at moneysupermarket.com, believes savers should "treat variable bonus rates with caution as rates may drop quickly", he said: "Savings rates are highly inflated at the moment because banks and building societies are still desperate for our cash.
"If you go for a deal that offers a fixed bonus you at least have some peace of mind."
Currently, according to the price comparison site, some of the most popular easy access accounts with a fixed bonus include ING Direct's Online Saver, which is offering a 2.70 per cent bonus (bringing the rate to 3.20 per cent) for the first 12 months, while Birmingham Midshires is offering a bonus of 2.65 per cent for the first year.
Meanwhile, Citibank's Flexible Saver and Sainsbury's Finance Internet Saver are offering bonus rates of 3.10 per cent and 2.90 per cent for the first year respectively.
Savers can expect to receive an estimated £90 in interest payments in the first year on accounts with an interest rate of around three per cent for the first year.
Mr Mountford urges savers to keep checking their accounts to ensure they get the best deal: "Those savers who take out bonus rate savings deals should also take note of when the bonus ends and be prepared to switch accounts once this happens. A really savvy saver can use bonuses to significantly boost their returns as long as they are willing to put in a little effort."
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