The bank has confirmed it will not close its final-salary schemes but will cap the amount of salary increases that are pensionable at either 2% annually or the rate of inflation, whichever is lower.
The firm also plans to reduce the lump sum payable on early retirement for those members opting to take an immediate undiscounted pension.
A spokeswoman told HR magazine the changes were to control the risks and cost of running the schemes.
Neil Roden, head of HR at RBS, said: "The rising cost of pension provision is an issue for RBS and for all companies at this time. Only one third of our staff are members of the UK defined-benefit pension scheme, which we closed to new members in 2006.
"This is an expensive scheme for our shareholders to fund and a generous one in comparison with the market. The reforms we are consulting on seek to strike a balance between reducing the costs and future liabilities of the scheme to the group and doing what we can to protect the welfare of existing staff and scheme members.
"It is a pragmatic and necessary course of action and not a decision the board has taken lightly."
Commenting on the announcement, Simon Banks, principal at Punter Southall, said: "Capping pensionable salary increases is one option available to employers, to control cost and risk within a pension scheme, which we have seen a number of less high-profile employers do recently. From the employer's perspective, it means that future salary increase decisions can be made without concern for the impact on pension costs.
"Within banking generally, there is a shift towards salary and away from bonus. This change would allow such a shift to occur without granting expensive pension windfalls. But the potential savings for those already on very high salaries should not be overstated as most schemes have retained a cap on pensionable salaries (the ‘earnings cap'), currently £123,600, for members who joined after 1989."
RBS is in consultation with trade union Unite on the proposals and expects the process to be completed by November.
But Unite has called the changes a ‘body blow' to staff.
The union's senior representatives at the bank will meet tomorrow (Thursday 27 August) to decide the most appropriate course of action to take in response to the announcement.
Rob MacGregor, Unite national officer, said: "Unite will support its members in any action they choose to take to defend their pensions. The union will be meeting again with RBS and we expect there to be meaningful negotiations over these changes.
"Against the backdrop of Sir Fred Goodwin's bumper pension these planned changes add insult to injury to the workers paying the price for a crisis for which they hold no responsibility.
"RBS staff, who already face great uncertainty with the possibility of major job losses, now face a future with severely reduced retirement benefits."
