Employee and Employer Contributions
401(k) plans consist of contributions made by both the employee and the employer. While the employee’s portion is always 100% vested, employer contributions may be subject to a vesting schedule. That means some of the employer funds might not belong to the plan participant yet—and may not be divisible until the vesting is complete.
Make sure your QDRO clearly states which contributions are going to be divided and whether it includes only the vested portion of the employer’s funds or anticipates future vesting.

