Previously, the Pension Plan Document (governmental plan) provided for a 5% COLA benefit, which, on an annual basis, was factored into the Plan's Normal Cost. Employee contributions (5-6% of their pre-tax gross wages) were deducted from that Normal Cost, and the employer paid the balance in the form of Annual Required Contributions (ARC). This process had went on for 15 years when the employer successfully reduced the COLA benefit from 5% to 2.5%, retroactively.
As a result, Plan assets that were reserved for a potion of the 5% COLA were now used to offset the employers future ARC. This description may be over simplified, but did this offset violate the Exclusive Benefit Rule?
I should add, because this Plan is situated in the State of Michigan, there are statutory requirements that require Plan assets to be held for the exclusive benefit of Participant's and Beneficiaries (PA 314).