Storing when bonuses are earned as compared to when they are paid.

Background:  We are on R12.1.3 RUP5.  We don't use Oracle payroll, but do store pay elements for sending out via interfaces to payroll providers.

Question:  We usually pay out bonuses and incentive plans well after the time period in which they are earned.  For example, the bonuses earned during Q1 will get paid out sometime during Q2.

What is a good way to indicate in HCM when the bonus was earned?   Ideally, capture a start and end date.  For example, enter Jan 1 as the start date and March 31 as the end date as the earned period for bonuses earned in that quarter.