Legal Question in Business Law in California

Re: returning money from over payment when I retired

There is no easy answer. Sometimes overpayments must be repaid under a restitution or 'unjust enrichment' theory, and other times either a 'detrimental reliance' or a 'discharge for value' theory can be invoked to relieve the payee of a duty of restitution. The former theory requires that the payee have no knowledge that he was being over-paid and no taint of negligence for not knowing ....... in other words, if your bookkeeping was sloppy, and with decent books you would have known the amount was too much, you would not be entitled to keep the excess.

Application of the theories to your facts goes way beyond what can be covered on a bulletin board and would be good material for a legal debate or a bar examination question.

In sum I'd say you would be most likely to win if sued for the money if all of the following are true: (1) You had no notion you were being overpaid at the time; (2) You didn't have any records (such as annual statements from the fund) that, had you bothered to look, would show the right amount, thus tipping you off to the overpayment; and (3) You relied on the amount being correct and spent, or committed, the excess funds so that making restitution would be a hardship.