Telecoms giant BT wanted to switch the measure by which pensions increase from the retail price index to the consumer price index, but the High Court has ruled against this change.
Pension liabilities could reduce by £30bn if those using RPI were able to switch to CPI, according to research by consultancy firm LCP.
The BT case was taken to the High Court in December last year. On Friday, the High Court ruled that, under the terms of its pension scheme rules, the telecoms company cannot swap the index used to increase pensions for the defined benefit fund's Section C members, who would have been affected by any changes.
The court said that RPI had not become invalidated and had not ceased to be published.
Prospect, the union that represents managers working for BT, said that it welcomes the ruling.
Philippa Childs, Prospect national officer, said: “Prospect has consistently campaigned against changing indexation of pension schemes from RPI to CPI, as CPI is normally around 1 per cent lower than RPI."
“The outcome of this case is welcome as this action has caused anxiety among active and deferred members and pensioners," she added.
“However, BT has told members of the scheme that it will be considering next steps after the ruling, including the possibility of an appeal. Prospect will be closely monitoring the actions of BT to ensure that our members' views are heard and taken into account.”
The union is also in the process of finalising a new pension deal on behalf of the BT managers it represents who are working members of the BT pension schemes.
