According to Lawyers.com, sentencing for aiding and abetting includes probation, fines or prison time. Yahoo! Voices mentions that prison sentencing is up to 15 years. The sentence for aiding and abetting depends on the state. A person who aids and abets stands to be sentenced with the same punishment as the actual perpetrator under federal law, and many states follow the same guideline. Other states consider it a lesser offense.
According to Shouse California Law Group, California is one state where a person who aids and abets is charged with a crime in the same way as the perpetrator. For instance, if a man draws a map to show the best way to rob a bank, that man stands to receive the same sentence as the person who did the actual robbing. The same principle applies to murder charges in California. If a person is convicted of aiding and abetting a murder suspect, the helper potentially faces the same punishment as the murderer, which amounts to life in prison.
Lawyers.com further notes that telling the police that someone is about to commit a crime helps a person avoid legal trouble. Never help an offender after a crime has been committed. Yahoo! Voices also notes that withholding information from the police about a crime means potentially being charged with obstruction of justice. However, it can be difficult for prosecutors to win an aiding and abetting case when there may be little proof that the party in question actually knew about any wrongdoing -- unless there is witness testimony, a conviction is unlikely.