1. Employee Contributions vs. Employer Contributions
Employee contributions are typically 100% vested from day one. However, any employer matching or profit-sharing dollars may be subject to a vesting schedule. The QDRO needs to clearly state whether the alternate payee will receive a share of just the vested balance or also a proportion of non-vested amounts as they become vested.
In many corporate 401(k) plans, a participant earns full ownership of employer contributions over a period of years — common vesting schedules include 3-year cliff or 6-year graded options. Make sure your QDRO handles this correctly to avoid disputes later.

