Coordination of Union and Company sponsored plans

[Guest brewbren]

A company sponsors a profit sharing 401(k) plan covering both union and non-union employees. Several of the company's employees (including HCE/key employees) are members of the union and participate in a union-sponsored defined benefit plan, to which the company contributes. Under the 401(k) plan, the union employees may contribute their own money, but are not eligible for any employer contributions.

1. For 415 limit purposes, is the union plan treated as separate, or as another plan of the same employer (requiring a test of the combined benefits)?

2. When calculating the 404 deduction limits for the 401(k) plan, which compensations are included (i.e., do you include union employees' compensation?), and is the limit 15% based only on the 401(k) plan, or 25% (using combined contributions to the 401(k) and union plan)?