Overpaid £500 by employer, employer has budget of £30 billion per annum, but to me it is still a lot of money, would feel guilty keeping it. Do I give it back or wait for them to ask for it back? EDIT > Thanks for the majority of honest people confirming what I had thought was best, told them about their error, feel better now. Would have been living in guilt otherwise. The warm fuzzy feeling was worth £540 to me, would only have spent it on a couple of meals anyway.