Borrowers’ lending rates could more than treble by Christmas as fixed interest mortgages started when rates were at record lows begin to expire, driving up household costs and increasing pressure on the property sector.

Fixed rates that dipped to record lows of between 1.95 per cent and 2.09 per cent in 2020 are on course to revert to more than 6 per cent in the fourth quarter as lenders pass on rises in cash rates.