Banks have cut deposit rates and increased the profits they make on mortgages even though the overall cost of borrowing has remained the same since the summer.
New figures suggest banks are protecting their bottom lines at the expense of savers and borrowers as interest rates peak.
Banks are preparing to post windfall profits after 14 base rate increases to curb inflation.
Losers: Lenders have been criticized for using rising interest rates as a cover to increase profits by squeezing savers and fleecing borrowers.
NatWest will reveal on Friday that its net interest income – earned on the difference between what it pays to savers and what it charges to borrowers – jumped from £9.8bn to £11bn last year.
Lenders have been criticized for using rising interest rates as a cover to boost profits by squeezing savers and fleecing borrowers.
The base rate has been at 5.25 percent since August, but that hasn’t stopped the banks.
The average margin they earn on a five-year mortgage has risen from 1.27 percentage points in June to 1.79 last month, according to investment bank UBS.
But one-year deposit rates are at 4.88 percent, down from a peak of 5.33 percent in October.