Employee vs. Employer Contributions
This 401(k) plan likely includes both employee deferrals and employer matching or profit-sharing contributions. In most cases, the QDRO only divides the vested portion. Make sure your attorney or QDRO drafter reviews the vesting schedule before finalizing the agreement.
If your divorce agreement awards 50% of the account, it should specify whether that includes only employee-defined contributions or also employer contributions. The plan administrator will only divide what the participant is legally entitled to at the time of divorce or QDRO, depending on the chosen valuation date.

