How is deductibility determined (how is compensation for deductibility

[John A]

Some employees in a union 401(k) plan have compensation and deferrals in the plan during a plan (and same) tax year. During the year, they transfer to non-union status and have compensation and deferrals in the non-union 401(k) plan. Normally, full year compensation is used for determining the deductibility limit. Is full year still used for both union and non-union deductbility limits? How do the deferrals in each plan affect the deductibility limit for each plan?