Splitting Contributions and Account Balances
With 401(k) plans, account balances include both employee contributions (contributed directly out of the paycheck) and employer contributions (matches, profit sharing, etc). In a divorce, you can choose to divide just the marital portion, which often includes assets earned during the marriage.
It’s critical to specify whether both employee and employer contributions should be divided. Some spouses also want earnings and losses included for the period between separation and plan division.

