Guideline plans allow any employee, whether full-time, part-time, seasonal, interns, etc. who are W-2 employees to be eligible to participate as long as they meet the age and service eligibility requirements you set for your plan.
Guideline plans offer two requirements as it pertains to eligibility: age of employee and months of service. You can request to change either or both of these requirements before the Plan Start date. Outside of those requirements, all W-2 employees, whether full-time, part-time, or temporary, will be treated the same as it relates to eligibility to participate in the Guideline 401(k) plan because we're not able to exclude any classes of employees specifically.