An employee is eligible to participate in a SEP IRA if he or she is at least 21 years old and has worked for the company in three of the last five years, and received at least $600 in compensation during the year.
As an employer, you don't have to fund contributions every year. But when you do choose to make contributions, you must contribute not only to your own SEP IRA, but the SEP IRA of every eligible employee.