I just got a Simple IRA funded today. The effective date of the plan was 05/18/2021. The employer agreed to match the first 3% dollar for dollar. But since we started mid way through 2021, I have a question. What is the start date for measuring compensation. Should it be 1/1/2021, 05/18/2021 (the day the adoption agreement was signed) or 08/26/2021, the date of the first contributions?