This oversight could cost your loved ones dearly.

Something seemingly so easy as to declare the beneficiary of your 401k has caused heartache for many unsuspecting heirs, who are unintentionally left with nothing.

Take the case of Ben Langford, who worked at a privately owned company for 25 years. He named his wife of 38 years the beneficiary of his 401k account in the event he died before her. As it turned out, however, she died first.

Consequently, Ben smartly updated his account, naming his three grown children as the co-beneficiaries of his account.