Final answer:
The statement is false; both pension and postretirement benefit plans use the corridor approach to amortize gains and losses when they exceed the 10% threshold.
Step-by-step explanation:
The statement that unlike pension accounting, the gains and losses from changes in the Accumulated Postretirement Benefit Obligation (APBO) or the value of plan assets are not subject to amortization using the corridor approach is false. In pension accounting, both the APBO and the value of plan assets can experience gains and losses resulting from changes in actuarial assumptions, market performance, and other factors. According to the corridor approach, if the cumulative gains and losses exceed 10% of the greater of the plan assets or the benefit obligation, this excess amount must be amortized over the average remaining service period of employees. Therefore, like pension accounting, postretirement benefit plans also utilize the corridor approach for amortizing gains and losses.