1. Employee vs. Employer Contributions
The total value of a 401(k) plan often includes both employee salary deferrals and employer contributions. In divorce, only marital contributions are typically subject to division. That might mean only a portion of the account balance is shared.
Employer contributions may also be subject to vesting schedules, which can cause confusion. If some employer contributions are unvested as of the cut-off date (e.g., date of separation, filing, or divorce), they may not be divisible—depending on state law and your divorce judgment.

