Idaho CDL Study Guide
Idaho issues commercial driver licenses through the Idaho Transportation Department (ITD) Division of Motor Vehicles. The state follows federal CDL rules in its Commercial Driver's License Manual. You can drive a commercial vehicle inside Idaho at 18. You must be 21 to drive across state lines or carry hazardous materials.
Key Idaho numbers
- Minimum age (intrastate): 18
- Minimum age (interstate or hazmat): 21
- CLP hold before skills test: at least 14 days
- General Knowledge passing score: 80%
- General Knowledge test: ~50 questions
- Air Brakes test: ~25 questions (required if your vehicle has air brakes)
- Combination Vehicles test: ~20 questions (required for Class A)
Topics on the Idaho General Knowledge test
- Vehicle inspection (pre-trip, en-route, post-trip)
- Driving safely (speed management, space management, hazard perception)
- Transporting cargo safely
- Air brakes (if your vehicle is air-braked)
- Combination vehicles (Class A)
If you fail a test
If you fail a CDL knowledge test in Idaho, the $5 per-test fee applies again. For skills test retakes, the county collects $10 each plus the CDL Examiner's fee. See the ITD CDL page for current details.
Frequently asked questions
How old do I need to be to get a CDL in Idaho?
You must be at least 18 to drive a commercial vehicle inside Idaho. You must be 21 to drive across state lines or carry hazardous materials.
How long must I hold my Idaho CLP before the skills test?
You must hold your Commercial Learneru0027s Permit for at least 14 days before you can take the CDL skills test.
How much does an Idaho CDL cost?
The CLP is $29, each written test is $5, the skills test is $10 (plus Examiner fee), and the 4-year CDL is $40 (or $60 for 8 years).
Do I need to take Entry-Level Driver Training in Idaho?
Yes. If you are getting your first Class A or B CDL, or your first H, P, or S endorsement, you must complete federal ELDT from an FMCSA-registered provider.
Do I need a DOT medical card to get an Idaho CDL?
Yes. You must complete a DOT medical exam and self-certify through ITDu0027s online system.
What is the official Idaho CDL manual?
The Idaho Commercial Driveru0027s License Manual (July 2025) is the official study guide. You can download it free from itd.idaho.gov.
Free practice
Start an Idaho General Knowledge quiz →
Sources: Idaho CDL Manual PDF (July 2025) ITD Commercial Driveru0027s License page Ten Steps to getting an Idaho CDL ITD CDL Self-Certification of Medical Status