Often, distancing from the family and lying happen together. It is common that by the time a teen gets caught lying, they have already been lying for some time. Struggling teens will often lie about things like what time they are going to be home from school, who they are going to be with, where they are going to be, what time they will come home on a weekend night, how they are doing in school, whether or not they have homework, if they did their chores, etc. These are just a few examples of some of the things a teen may try to hide as their life starts changing for the worse. Teens have a very strong sense of right and wrong. If they are defying boundaries set by parents, they are aware of it and they will use every means imaginable to hide their objectionable behavior. Often by the time a teen is consistently caught lying the shift in lifestyles has already begun.
If you are absolutely sure your child is lying, it is important to deal with the situation calmly and immediately. Try to find out what is motivating them to lie to you. Probe for the reasons the child may have lied instead of simply defaulting to lecturing and punishment. Let them know that lying will damage relationships which are based on trust and communication. Explain in very clear terms the consequences of future lying.