Research from the Central Bank has found that the average interest rate on variable rate mortgage loans is just under two percentage points higher than the average for tracker loans.
The research examined movements in variable rate home loans over the past few years.
The bank said that, up to the end of 2008, the difference between tracker and variable mortgage interest rates was "almost zero".
It said the widening of the gap was due to less competition and the higher cost to banks of attracting deposits. The bank also said some banks appeared to be charging higher variable rates to compensate for higher mortgage arrears and losses on tracker loans.
It said that, since 2009, the bulk of new mortgage lending has been on variable rates, in contrast to the property boom era, when trackers accounted for more than three-quarters of new lending.
Variable rate mortgages account for around a third of outstanding mortgage loan balances.
