Illinois CDL Written Test — Questions, Cost & Study Tips (2026)

Studying for your Illinois CDL written exam? Here is what applicants typically need to know before visiting Illinois SOS.

How many questions on the Illinois CDL test?

Illinois general knowledge written exams commonly include about 50 multiple-choice questions for the core CDL knowledge test. Endorsements such as air brakes, combination vehicles, hazmat, and passenger are separate written tests if your license class requires them.

PassCDL mirrors this structure: start with general knowledge, then add endorsement practice for the tests you need.

Illinois CDL test cost (approximate)

Written exam fees at Illinois SOS are typically $25–$40 per attempt (varies by office and endorsement). Failing and retesting can cost more than a month of PassCDL Pro — many students prefer unlimited practice before test day.

Illinois study tip

Illinois SOS CDL knowledge tests must be passed before behind-the-wheel training for your license class.

Free IL CDL practice test

Use our Illinois CDL practice test for scored questions and explanations. PassCDL Pro adds full exam simulations, all endorsements, and unlimited retakes.

See also: How many questions on the CDL test? · CDL general knowledge study guide

Educational practice only — not affiliated with Illinois SOS or any state DMV.