One in five homeowners could save money by switching mortgage lenders.
The Central Bank says 27,000 mortgage holders could save up to €10,000 over the lifetime of their loan.
More than 100,000 people on variable rate mortgages could make savings on their loans by switching to a lender with a lower interest rate.
Research from the Central Bank says around 26,000 people could reduce what they are paying by around €1,000 a year if they switched provider.
However, half of mortgage holders cannot find a cheaper rate - mainly because they are on a tracker.
While many customers are put off switching because they think it will be expensive.
One-third of homeowners could make savings by switching but are not in a position to do so because of arrears or high loan to value ratios.
Currently just 38 homeowners a month are switching at the five main banks.
Michael Dowling is a partner at Abacus Finance. He told Newstalk Breakfast says people should challenge their banks.