Use this email template to announce performance bonuses to your employees. What is a Bonus Plan?A bonus plan is an agreement between the employer and employee to pay out a predetermined amount of money based on performance. The Frequently Asked Questions (FAQs) provided below highlight topics and specific questions that are often asked of the Illinois Department of Labor (IDOL). The bonus letter should include details such as the bonus amount, the reason for the bonus, and any performance criteria used to determine it. What is a Bonus Plan? A bonus plan is an agreement between the employer and employee to pay out a predetermined amount of money based on performance. Filling out this document is straightforward. How often must an employer pay wages? Year-End Discretionary Bonus: Equivalent to one month's salary.