Employee vs. Employer Contributions
One of the first questions in dividing a 401(k) is: what share of the balance is marital? In most states, contributions made during the marriage are considered community or marital property. Both employee (your paycheck deductions) and employer (company match) contributions need to be accounted for.
However, employer contributions may be subject to vesting schedules. If the non-employee spouse is awarded a portion of the account that includes unvested employer contributions, those amounts can be forfeited if not fully vested at the time of division.

