UK - Changes to defined benefit indexation have saved FTSE100 schemes more than £15bn($23.6bn), Towers Watson estimates.
It said many of the country's largest companies are preparing to record "record windfall gains" as a result of the RPI to CPI switch.
The consultant said the average reduction in scheme liabilities for larger firms is about 2.5%. However, the impact for companies with 31 December 2010 year-ends ranges from 0.5% up to 6%. It added those with sizeable pension liabilities are more likely to record a higher-than-average effect.
Towers Watson head of UK pensions John Ball (pictured) said: "The government's policy change has transferred wealth from pension scheme members to sponsoring employers, who are busy quantifying these windfalls on their balance sheets."
He explained the impact depends on the scale of legacy pension promises, scheme rules and how the membership is made up.
"Some companies won't be affected at all, and we've seen those who are estimate gains that range a few million pounds to the billions."
However, Ball added in most cases savings are limited because employers expect to use CPI only between the time a member stops earning new benefits and when they retire - but there are exceptions.
"This is determined by the wording used when scheme rules were drawn up several years ago, which can be a historical accident."
The consultant polled 42 of its largest clients who have agreed preliminary accounting assumptions for 2010.
Of these, 28 said the way their scheme rules are written means at least some pension increases will now be based on CPI inflation rather than RPI inflation. However, only five said all pension increases would now be CPI-based.
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