Over a third of British borrowers do not intend to seek out a new deal on their mortgage when their cheaper rate expires, which could be costing them thousands of pounds a year, according to Abbey bank.
Abbey estimates that 800,000 Britons are coming to the end of their short or medium-term mortgage deal, and a third of these will not remortgage.
Instead, most will move onto a Standard Variable Rate, which could increase repayments by as much as £148 a month.
Abbey's research has also revealed that only one in three borrowers know when their deal ends, and 13 per cent do not even know what their existing interest rate actually is.
Gary Hockey-Morley, Abbey's director of mortgages warned borrowers to be more aware of their deals.
"All borrowers coming to the end of a deal should look around for their next mortgage deal as soon as they can," he said.
"Shopping around is crucial because rates and fees vary greatly between lenders and can change quickly.
Borrowers' lack of knowledge when it comes to rates and remortgaging could mean that most have not noticed that mortgage rates have risen over the past two years, by an average of 1.29 per cent.
"It is really important that borrowers find a deal that suits their individual needs, remortgaging is easy to do and could result in a significant monthly saving," said Mr Hockey-Morley.
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