Lying is an impulse control thing. People with ADHD might tell obvious untruths because they fear there will be consequences for doing something or not doing something, and without really thinking about the situation they snap to a lie. I know I’m much more honest as an adult even when I’ve done messed it all up, but as a kid I think most things I said were not true. I’m sure that sucked for those around me. It took a process of thinking about how lies make me feel about myself and how they make other people feel in order for me to learn to control that impulse. And controlling that impulse is a skill that has to be learned, there are some techniques out there. I know it’s going to be frustrating and will be a long-term project to overcome this, but acknowledge your child when she tells the truth let her know how it made you feel that she did, and hopefully this will help her connect what she says to the way people feel about her. When you’re in trouble a lot (and kids with ADHD are) it’s easy to feel drawn to positive reactions and knowing that what you’re doing is something that gets other people’s approval.