Employee and Employer Contributions
Most 401(k) plans include both employee deferrals and employer-matching contributions. However, employer contributions often come with a vesting schedule. This means that the participant may not have fully earned (vested in) all the employer money as of the divorce cut-off date.
The QDRO should clearly specify whether the division includes only vested contributions or if it will be adjusted to include amounts that vest later. Failing to clarify this often leads to disputes or delays in processing.

