Fearon, who has written to Rachel Reeves to express his concerns, is the latest building society boss to back the Mail's Hands Off Our Cash Isas campaign, standing up for the millions of savers who have nearly £300billion in the accounts.
Richard Fearon, chief executive of Leeds Building Society, also said hundreds of customers had raised concerns that the tax-free savings limit will be slashed.
Trade body the Building Societies Association has warned Reeves scaling back the tax break would cause mortgage rates to rise and could lead to a housing market downturn.
'If cash Isa funding was removed, mortgage rates would become more expensive for borrowers,' Fearon said in his letter to Reeves, seen by the Mail.
Warning: Leeds Building Society boss Richard Fearon has written to Rachel Reeves to express his concerns.
