Technically, yes there are lasers that are capable of treating tanned skin. These are the same lasers that are used to treat darker skin types. However, if you want an effective and comfortable laser hair removal treatment you need to be as close to your natural skin coloring as possible. The pigment that builds up as your skin gets tan is the same pigment in your hair that is being targeted by the laser. So, the more tan you have, the more your skin becomes a target. Because of this, your settings will have to be lowered to prevent burning your skin. Obviously, this results in a less than optimal or more uncomfortable treatment. If you want good quick cost-effective results you need to choose between being hair free or tan during the process.