If government reduces pensions tax relief to 20%, the ‘squeezed middle' could be £3,000 worse off per year in retirement, says Fidelity Worldwide Investment.
A higher rate tax-payer investing £4,000 into a personal pension could lose £56,000 over a period of 20 years of saving.
At today's rates, that compares to an annuity of almost £3,000 per year for a couple retiring at age 65, or £3,500 a year for a male retiring at age 65.
Investment director, Tom Stevenson, said: "It is concerning that the coalition would be considering such an attack on people taking responsibility for their financial futures. The message it sends out about the Government's attitude to saving is wholly wrong."
From April, changes to higher-rate tax and personal allowances will mean anyone earning over £42,476 will pay 40% tax. The Institute of Fiscal Studies estimates one in four people could be in this bracket by 2015.
In addition, Lib Dem MPs are calling for government to halve tax relief on pension contributions for high earners from 40% to 20%, in order to raise the income tax threshold to £10,000.
Stevenson added: "The beneficiaries of pension contribution tax relief are an easy target for a government trying to make savings. Workers who benefit from higher rate pensions tax relief are often wrongly thought to be ‘fat cats', but actually in the main they are just ordinary people trying to do the right thing.
"Someone earning £45,000 would not consider themselves a ‘fat cat' by any means but they would be caught by this measure and rightly feel aggrieved about the way in which their attempt to make prudent provision for their retirement is viewed by Government. Therefore, we are urging the Government to consider the impact it would have on long-term savers who are doing the right thing in saving for their future. It should reject this option."
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