Employee Contributions
These are typically 100% vested immediately, so they’re generally subject to division by a QDRO regardless of length of employment. If the participant was contributing their own salary toward the plan during the marriage, those funds are marital and can be divided.
Employer Contributions
This is where things can get tricky. Most 401(k) plans, especially those in general business industries like this one, include a vesting schedule. That means the employer’s matching contributions may not fully belong to the employee (or be divisible with a former spouse) until a certain number of years have passed.
You need to determine what portion of the employer contributions are vested. If they’re not yet vested at the time of divorce, they may be forfeited if the participant leaves the company or may not be available to divide.