为什么在计算int expense时候不需要加past service cost？

问题如下：

If XYZ prepared its financial statements under US GAAP, the total amount recognized by XYZ on the income statement related to its DB plan for fiscal year 2024 (assuming the company chooses not to immediately recognize the actuarial loss and assuming there is no amortization of past service costs or actuarial gains and losses) would be closest to:

选项：

20

59.

530.

解释：

A is correct. Under US GAAP—assuming the company chooses not to immediately recognize the actuarial loss and assuming there is no amortization of past service costs or actuarial gains and losses—the components of periodic pension cost that would be reported in P&L include the current service cost of 200, the interest expense on the pension obligation at the beginning of the period of 2,940[= 7.0% × (42,000)], and the expected return on plan assets, which is a reduction of the cost of 3,120 (= 8.0% × 39,000). Summing these three components gives 20(=200-3120+2940).