If you have a residual limb, you know how hard it can be to find the right fit and comfort you long for in a prosthetic sock. Your doctor may prescribe you a sock with an L8420 medical billing code. When a doctor prescribes a sock with a medical billing code, that code is used as a guideline for insurance companies, so they know how much to pay out on the sock. Socks which fall under the billing code L8420 have regulations and standards that must be met in order to qualify as those that billing code. To learn more about the L8420 medical billing code, see information below.