Your doctor needs to write a letter outlining the medical necessity of tinted windows, which you'll submit to the Secretary of State's office. The certification must be carried in the vehicle at all times.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. Window tint medical exemptions allow you to install darker tint on car windows. See all requirements for medical waivers, certificates and exceptions. Edit, sign, and share illinois tinted window certification online. No need to install software, just go to DocHub, and sign up instantly and for free. You can find a Tinted Window Certification form here (.