Stop believing everything he says. Even when you know he's telling the truth. Make him prove everything. But first, sit him down and tell him that since he lies about everything that you can no longer trust him and that he will have to prove the truth of everything to you. And since you can't trust him, you will be calling his friends parents to find out if he got there, and what is going on over there. Using the love and logic approach, the logical consequence for such extensive lying is no trust for him at all. Did he do his homework? Make him show you it and he has to have a note from his teachers telling what the homework is (hopefully the teachers will work with you on this). He might be a little old for this, but make a chart where he gets to earn back priveleges and trust for each time he tells the truth. If he lies, he loses points on the chart big time. It might be a good way for him to learn that even one lie (in real life) cost trust way more than telling the truth one time helps to build it back. Good luck to you!