Iowa CDL Study Guide
Iowa issues commercial driver licenses through the Iowa Department of Transportation. The state follows federal CDL rules in its Commercial Driver's License Manual. You can drive a commercial vehicle inside Iowa at 18. You must be 21 to drive across state lines or carry hazardous materials.
Key Iowa 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 Iowa 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 or skills test in Iowa, you may schedule a retake at an Iowa DOT service center. See Iowa DOT for current retake details.
Frequently asked questions
How old do I need to be to get a CDL in Iowa?
You must be at least 18 to drive a commercial vehicle inside Iowa. You must be 21 to drive across state lines or carry hazardous materials.
How long must I hold my Iowa CLP before the skills test?
You must hold your Commercial Learner Permit for at least 14 days before you can take the CDL skills test.
How much does an Iowa CDL cost?
The CLP is $12. The CDL is $8 per year (up to 8 years, total $64). Endorsements are $5 each.
Do I need to take Entry-Level Driver Training in Iowa?
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 Iowa CDL?
Yes. You must complete a DOT medical exam and submit your Medical Examineru0027s Certificate to Iowa DOT.
What is the official Iowa CDL manual?
The Iowa Commercial Driveru0027s License Manual is the official study guide. You can download it free from iowadot.gov.
Free practice
Start an Iowa General Knowledge quiz →
Sources: Iowa CDL Manual PDF Iowa DOT Commercial Drivers page Iowa DOT Commercial Learner Permits (CLP) Iowa Driveru0027s License Fees