After a bill is passed by congress how long does the president have to sign it?

He doesn't have to sign it at all. He can sign it, in which case it becomes law, or he can refuse to sign it, in which case it generally doesn't but that is where the time limit comes in. If he wants to veto the law then he has ten days to send it back ti congress with his reasons for not signing it. That gives them the chance to override his veto. But if he doesn't send it back within that amount of time then it becomes law anyway just as if he had signed it. There is one exception to that though. If the congres adjourns before the ten days is up so that the president can't send the bill back to them, then, if he doesn't sign it, it doesn't become law and they can't override him. That is called a pocket veto because when Abraham Lincoln used it for the first time he described it as just sticking the bill in his pocket.

Michael Montagne