Employee vs. Employer Contributions
In a 401(k), contributions may come from both the employee and the employer. Usually, employee (participant) contributions are automatically considered marital property if made during the marriage. However, employer contributions are treated differently. Most employer contributions are subject to a vesting schedule, which can affect whether the non-employee spouse is entitled to any portion of that money.
During divorce, only the vested portion of employer contributions is usually divisible. So if the participant is not fully vested, the QDRO must clearly define what happens to any unvested funds.

