1. Employee vs. Employer Contributions
One of the first questions in dividing a 401(k) is: what part of the account is divisible? Typically, both employee and vested employer contributions are available for division—though timing matters. If the employer has matching contributions, some or all of those funds may be subject to a vesting schedule. If the participant is not yet fully vested, part of the employer match may be forfeited after divorce unless accounted for carefully in the QDRO language.

