If your mortgage is reviewed on an annual basis you could be facing a £1,000 jump in repayment costs, Charcol has warned.
2004's four interest rate hikes could all be factored in at once seeing mortgage holders payments rise by as much as 20 - 25 per cent from next year, Charcol has said.
A £100,000 mortgage on annual review could have its monthly interest payments jump £83, equivalent to £1,000 a year, if the lender's interest rates rose at the same rate as the Bank of England's base rate.
"There are still many borrowers in the UK who have their mortgage structured on an annual review basis," said Ray Boulger, senior technical manager at Charcol.
"This means any interest rate changes over the course of the year are amalgamated and applied to the mortgage at the start of each New Year.
"As payments will have been calculated on a lower interest rate at the start of 2004, borrowers on annual review will have a shortfall to make up next year.
"Even those who are fully prepared for the leap in their mortgage payments would be foolish to not look at whether they are getting the very best value from their loan.
"Borrowers who do not have early repayment charges should contact their lender and ask what better deals they can offer, and then compare these deals with others in the market.
"Apathy on the largest financial commitment many of us will ever have just does not make sense."To read how to switch mortgage providers, click here.
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