Millions of savers are being cheated out of up to £920 a year tax-free interest on their cash Isas, a Money Mail investigation has discovered.

Millions of savers are being cheated out of up to £920 a year tax-free interest on their cash Isas, a Money Mail investigation has discovered.

We have compared the interest rates banks and building societies pay on taxed, fixed-rate savings bonds with that paid on fixed-rate cash Isas.

Nearly every bank and building society  pays less on cash Isas. In the worst case,  the difference is as much as 1.35 percentage  points.