Iowa CDL practice tests
Iowa spreads CDL testing across three separate channels rather than one, DOT service centers, county treasurer offices, and licensed third parties, and it requires those third party examiners to carry a $50,000 surety bond and pass an AAMVA certified examiner course before they can test anyone.
The written exams themselves are federal. Iowa decides the permit rules, the fees and who runs the skills test, but the knowledge you are tested on comes from 49 CFR Part 383 and is the same in every state, which is why the 145 questions here work wherever you apply.
What changes in this state
Commercial learner permit
Iowa requires a commercial learner permit to be held for at least 14 days before the skills and drive test, and the permit is valid for one year from issuance with no renewal.
Iowa Department of Transportation, Commercial Learner Permits, checked 2026-08-28
Fees
A commercial learner permit costs $12 through the Iowa DOT.
Iowa Department of Transportation, Commercial Learner Permits, checked 2026-08-28
Where you test
Knowledge and skills tests in Iowa are offered at DOT driver's license service centers, at some county treasurer offices, and through DOT authorized third party testers, all giving the same test.
Iowa Department of Transportation, Third-Party Testers, checked 2026-08-28
Every knowledge area
General Knowledge
Required of every applicant: inspection, control, space and speed management, hazard perception, emergencies and hours of service.
Air Brakes
Fail this and an L restriction bars you from any vehicle with air brakes, which is most of them.
Combination Vehicles
Coupling, the fifth wheel, off tracking and trailer swing. Needed for Class A.
Hazardous Materials
Placards, shipping papers, segregation and the security threat assessment.
Tank Vehicles
Liquid surge, baffles, outage and why a tanker rolls over so readily.
Doubles and Triples
Rearward amplification, converter dollies and coupling a second or third trailer.
Passenger Transport
Bus inspection, standee lines, passenger supervision and railroad crossings.
School Bus
Danger zones, loading and unloading, student crossing and evacuation.