When calculating PPC and TPPC …

Which of (1) amortization of past service costs and/or (2) actuarial gain or loss … must be added/subtracted?

Both CFAI and Schweser did a very good job of highlighting this. Have a read of the curriculum.

That is the exact hunt I don’t have time to go on. Consider it a quiz, if you know the answer.

It’s in the sentence… all the costs i.e amortization of past service costs are added to the periodic pension expense since its a cost. Remember this is only under US GAAP. Under IFRS all of the past service cost is expensed.

Actuarial Gains / Losses are part of remeasurement. Correct me if I am wrong but gains are added to OCI and Losses are deducted from OCI under US GAAP and amortised using the corridor method.

Under IFRS Remeasuremet is parked in OCI and not amortised.