First, you need to have a signed affidavit from a physician stating your medical condition and how it necessitates a tinted window. The certification must be carried in the vehicle at all times.The letter should include the name, credentials, and medical license number of the physician issuing the statement. The DMV gives medical authorizations to individuals seeking protection from the sun, so your local DMV may be a good starting point to obtain a form. Keep original signed form in the customer's case record. Attach a copy of signed. Window tint medical exemptions allow you to install darker tint on car windows. See all requirements for medical waivers, certificates and exceptions.