If all the FTSE100 companies still using the RPI inflation measure in their pension schemes were to move to using RPIJ, the combined pension deficit could fall by up to £20bn, LCP says.
The funding level of FTSE350 pension schemes tumbled to a four-year low of 83% after deficits grew by £4bn last month.
The Pensions Regulator's (TPR) updated defined benefit (DB) code of practice comes into force today.
STV has agreed an accelerated deficit recovery plan with trustees of its two defined benefit (DB) schemes after protracted negotiations.
The aggregate deficit of the Pension Protection Fund 7800 Index shrank from £109.0bn to £118.2bn last month according to figures released by the lifeboat fund.
FTSE350 companies saw their pension deficits rise £39bn in the past 12 months, according to Mercer.
Average IAS19 discount rates used by FTSE100 companies to calculate pensions deficits have risen for the first time in five years.
Deficits in FTSE350 pension schemes are at the lowest levels compared to the financial strength of their sponsors since before the last recession, according to PwC.
Fuller Smith and Turner will close its final salary scheme to future accrual next year, the company has announced.
Severn Trent is set to contribute £75m over two years to help plug the deficit of its defined benefit schemes.