Illinois CDL Test Questions 2026: Format, Topics and Passing Rules
Current Illinois CDL knowledge-test format for 2026, including the 30-question General/Core test, English-only testing, audio option, passing threshold, and retest rules.
Illinois publishes unusually useful detail about its CDL knowledge-test format. The most important number is official: the computerized General/Core knowledge test contains 30 standardized random multiple-choice questions.
General/Core knowledge test
Every CDL applicant must pass the General/Core test. Questions cover CDL laws, safe operation, vehicle knowledge, inspections, controlling speed and space, hazards, emergencies, cargo concepts, and other material in the Illinois CDL Study Guide.
Additional tests depend on the vehicle and job
- Classification/Combination knowledge for Class A combination vehicles.
- Air Brakes when seeking to operate vehicles equipped with air brakes without the applicable restriction.
- Passenger and School Bus for covered bus operations.
- Tank Vehicle, Doubles/Triples, Hazardous Materials, and other endorsements as applicable.
Passing score
Illinois requires at least 80% on CDL knowledge tests except the School Bus test, which has a higher state standard. Do not prepare only to scrape past the cutoff; the same concepts appear again during inspection, control, and road operation.
Language and audio options
The current Illinois Secretary of State CDL page says CDL knowledge and written tests are administered in English only. A computerized audio format can be requested, and further oral-test assistance may be available through facility procedures. Do not rely on older pages that imply normal CDL testing is offered in multiple written languages.
Retest rules have escalating consequences
Illinois applies waiting periods after repeated failures of the same exam. The current state page explains that three failures trigger a 30-day wait, six failures a 90-day wait, and nine failures a one-year wait, with additional fees after each three-failure waiting period.
Best preparation method
Study the current Illinois CDL Study Guide first, then use practice questions as a diagnostic tool. Review every missed answer until you can explain why the correct choice is correct rather than memorizing a letter.
Sources: Illinois Secretary of State CDL/CLP Testing section and current CDL Study Guide. Reviewed October 2026.