What of a particular period is principally determined based on benefits earned by participants during the period (service costs) less earnings on…

The question describes the primary components used to calculate net periodic pension expense under accrual accounting. "Benefits earned by participants during the period" directly refers to the service cost component. The phrase "less earnings on plan assets in excess of interest accretion of the projected benefit obligation" refers to the net effect of two other major components: the return on plan assets (a credit/reduction to expense) and the interest cost on the pension obligation (a debit/increase to expense). Together, these elements form the core of the pension expense reported in a company's financial statements for a given period.

A. Obligatory adjustment expense: This is not a standard or recognized term within Generally Accepted Accounting Principles (GAAP) or International Financial Reporting Standards (IFRS) for pension accounting.

B. Payment accounting: This refers to cash-basis accounting, where expenses are recognized upon payment. Pension accounting is based on the accrual principle, recognizing costs as they are earned by employees.

C. Loss adjustment expense: This term is specific to the insurance industry and represents the costs associated with investigating and settling insurance claims, unrelated to employee pensions.

1. Financial Accounting Standards Board (FASB). Accounting Standards Codification (ASC) Topic 715, Compensation—Retirement Benefits. Section ASC 715-30-35-4 explicitly lists the components of net periodic pension cost, which include: (a) Service cost, (b) Interest cost, (c) Actual return on plan assets, (d) Amortization of prior service cost or credit, (e) Gain or loss, and (f) Amortization of the net obligation or asset. The question describes a combination of components a, b, and c.

2. International Accounting Standards Board (IASB). International Accounting Standard (IAS) 19, Employee Benefits. Paragraph 120 outlines the components of defined benefit cost, stating that an entity shall recognize components such as service cost and net interest on the net defined benefit liability (asset) in profit or loss. This aligns with the elements described in the question.

3. Spiceland, J. D., Nelson, M. W., & Thomas, W. B. (2021). Intermediate Accounting (11th ed.). McGraw-Hill Education. In Chapter 17, "Pensions and Other Postretirement Benefits," the text defines pension expense as a composite figure comprising several components, principally service cost, interest cost, and the expected return on plan assets.