Final answer:
Actuarial gains or losses are related to post-employment defined benefit plans, where future pension benefits are determined by employee factors and assumptions like life expectancy or retirement age. Defined contribution plans such as 401(k)s involve fixed employer contributions and do not carry the same actuarial risks.
Step-by-step explanation:
Actuarial gains or losses are primarily associated with post-employment defined benefit plans. These gains or losses can occur due to differences between the assumed and actual experience on pension plan assets or changes in the assumptions about future benefits, such as life expectancy or retirement age. Defined benefit plans promise a specified pension payment in retirement, which is based on factors like salary history and years of service. Unlike defined contribution plans such as 401(k)s and 403(b)s, where the employer contributes a set amount to an employee's retirement account, defined benefit plans guarantee a specific benefit at retirement and thus carry actuarial risks that can lead to gains or losses.
These actuarial gains or losses are not typically associated with short-term compensated absences, post-employment defined contribution plans, profit sharing, or bonus plans since those do not have the same level of actuarial prediction associated with retirement benefits guaranteed by employers.