Royal Bank of Scotland (RBS) has told staff they will have to work longer and contribute 5% of salary to their final salary pension.
About 42,000 scheme members have been told they will have to work an extra five years before reaching pension eligibility.
They will also have to pay in about 5% of their salary if they want to retire at 60 on full benefits. At present, the bank makes a significant 15% contribution while staff are not obliged to contribute at all.
Staff who do not want to contribute, or cannot afford to, can either continue working until 65 or take lower benefits at 60, the bank said.
Unite, the union, reacted angrily to the announcement.
Unite national officer David Fleming said: "RBS awards its executives millions in bonuses while many of its branch employees earn little above the minimum wage. With 28,000 workers receiving no pay rise this year, these changes will make access to the pension scheme unaffordable for many.
"This is yet another example of RBS failing to value its workforce in bank branches and back offices up and down the country."
The final salary pension scheme was closed to new members in 2006.
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