Employee vs. Employer Contributions
401(k) plans are made up of a mix of employee and employer contributions. Employee contributions are always 100% vested, which means they can be divided fully in a QDRO. However, employer contributions may be subject to a vesting schedule. This means the plan participant must work for the company for a certain number of years before that money becomes theirs.
If you’re the alternate payee (the spouse receiving a share), make sure the QDRO only divides the vested portion of employer contributions, unless otherwise agreed upon. A professional QDRO draft should clearly distinguish between the vested and unvested balances.

