If an employer has different plans (the same employer, I must specify); say for example, a

[Guest Enda80]

If an employer has different plans (the same employer, I must specify); say for example, a 401(k) plan for unassociated-with-the-union employees, a different plan for union employees, and a defined benefit plan (which serves to augment the 401(k) plan), how does that affect the determination of proper coverage?

[Effen]

Any employees subject to collective bargaining can generally be excluded for "coverage" testing and "non-discrimination" testing. The other participants would need to be considered when performing coverage and non-discrimination testing on the various plans.

[david rigby]

To elaborate on Effen's answer, the "collective bargaining" exclusion applies to where pension benefits are the subject of good-faith bargaining. Not exactly the same as "union". See IRC 410(b) and regs.