Which of the following pertains to variable pay eligibility?

Variable pay eligibility specifically refers to the criteria determining which employees qualify to receive variable pay components, such as bonuses or incentives, and the timing of these disbursements. Focusing on 'who is eligible and when' encapsulates the essence of variable pay eligibility by highlighting the importance of identifying the specific groups of employees that meet the necessary qualifications for receiving this type of compensation.

This option encompasses aspects such as performance metrics, job roles, or length of service that influence both eligibility and timing for the payout of variable compensations. Understanding this concept is crucial for effectively designing and communicating a compensation strategy within an organization.

The other options touch on related topics but do not directly address eligibility for variable pay. For example, merit increases relate to base salary adjustments based on performance, while vesting and tax implications pertain to how benefits are accessed and their financial impact rather than eligibility itself. Base salary adjustments are fixed and do not represent the variable nature of pay eligibility, which is contingent upon performance-based assessments or other variable measures.