If somebody pays money to you by accident, at what point can you keep the money?
If somebody pays money to you by accident, at what point can you keep the money?
Ethically, if it's not yours, you should pay it back.
Legally, it depends upon how the money came into your possession, and what cause of action might be used to bring it back -- breach of contract, fraud, a property-based claim, etc. -- and whether there are grounds to toll (extent) the limitations period. Look up the statutes of limitation for your state.