Employee vs. Employer Contributions
401(k) plans generally include employee deferrals and potentially employer matching or profit-sharing contributions. While employee contributions are always 100% vested, employer contributions might be subject to a vesting schedule.
That means if the employee spouse (also known as the participant) leaves the company before they’re fully vested, the ex-spouse (the alternate payee) can’t receive amounts that were later forfeited. This is critical to address correctly in the QDRO—overestimating available funds due to unvested amounts can lead to payout errors or delays.

