Employee and Employer Contributions
The Power System Engineering, Inc.. 401(k) Plan likely includes both employee salary deferrals and employer contributions. When dividing the account with a QDRO, only the marital portion is usually subject to division. This means the value accrued from the date of marriage to the date of separation or divorce—depending on your state law.
Employer contributions may be subject to a vesting schedule (see below), which can affect how much of those contributions are actually divisible.

