Iowa CDL practice tests

Iowa keeps commercial licensing inside the Department of Transportation itself, rather than handing it to a separate motor-vehicles bureau or a law-enforcement agency the way some neighbouring states do. The same department that builds and resurfaces the highways is the one that signs off on your commercial license, so the paperwork trail for a CDL runs through one roof rather than two.

What Iowa requires

Every figure below names the document it came from, so you can check it rather than take our word for it.

Passing score
80% 49 CFR Part 383, Commercial Driver's License Standards, 383.135
Minimum age (in-state driving)
18 years old 49 CFR Part 383, Commercial Driver's License Standards, 383.71
Minimum age (across state lines)
21 years old 49 CFR Part 391, Qualifications of Drivers, 391.11
Permit holding period
14 days 49 CFR Part 383, Commercial Driver's License Standards, 383.25

Fees change without notice, so we do not repeat them here. Check Iowa Department of Transportation for the current cost.

Iowa practice tests

The knowledge tests are set by federal rule, so the questions are the same wherever you sit them. What changes is the paperwork above.

What Iowa does differently

Much of the testing you'll sit is federal rather than Iowa-specific: Title 49 of the Code of Federal Regulations, Part 383, sets the knowledge exams, the endorsements and the required pass mark, and that's true whether you test in Des Moines or anywhere else in the country. Iowa's own contribution is more about geography than rules. The state has a lot of land and comparatively few people on it, so if you live in a rural county, the nearest testing site can mean a genuine drive rather than a short trip across town — plan the day around that rather than assuming you can fit it in before work.

Iowa also sits where two of the country's busiest interstate freight routes cross: I-80 running east-west and I-35 running north-south. A large share of the state's commercial drivers end up hauling loads over the state line at some point in their career, which is why the federal rule setting the interstate minimum age at 21, three years above the intrastate minimum, matters to so many Iowa applicants specifically.

Which tests you actually need

Everyone sits the general knowledge exam. From there it depends on the vehicle. Air brakes require their own test, and failing it does not block you from getting a license — it adds a restriction that stops you driving anything fitted with them. A trailer over 10,000 pounds means the combination vehicles test. On top of those sit the endorsements: tank, doubles and triples, passenger, school bus, and hazardous materials.

Hazardous materials carries an extra step none of the others do: a background check run through the Transportation Security Administration, on top of the written exam. That check runs on its own schedule, so start it early rather than leaving it until the rest of your paperwork is ready.

Before you book

You need a commercial learner permit before Iowa will let you sit the skills test, and federal rule requires that permit to be held for at least 14 days first. Use that fortnight to get the knowledge exams out of the way early, so a resit doesn't eat into time you need for the skills test itself.

We don't list fees on this page. Iowa sets and changes them without asking us first, and a number that's gone stale is worse than no number at all, so check the DOT's own page before you go. What you'll find here instead is exactly which questions the exams ask, and where in the rules each answer comes from.

Jump to a test

Every question on every one of these is free, and each answer names the handbook page it came from.

Other states

Cited to the page, every time.

Every question names the handbook, section and page it was read from, so you can check the answer instead of taking our word for it.

How we write these