According to the Department of Labor, you have a missing participant problem if:
1) You have more than a small number of missing or nonresponsive participants.
2) You have more than a small number of terminated vested participants who have reached normal retirement age but have not started receiving their pension benefits.
3) Missing, inaccurate, or incomplete contact information, census data, or both (e.g., incorrect or out-of-date mail, email, and other contact information, partial social security numbers, missing birthdates, missing spousal information, or placeholder entries).
4) Absence of sound policies and procedures for handling mail returned marked “return to sender,” “wrong address,” “addressee unknown,” or otherwise, and undeliverable email.
5) Absence of sound policies and procedures for handling uncashed checks (as reflected for example, by the absence of an accounting journal or similar record of uncashed checks, a substantial number of stale uncashed distribution checks, or failure to reclaim stale uncashed check funds in distribution accounts).
As with anything in retirement plans, you need a plan and a way how to handle missing participants. But before you can, you need to know you have a missing participant problem.