What's the Passing Score on the Idaho CDL General Knowledge Test?
40 out of 50 — 80% — passes Idaho's CDL General Knowledge test. The threshold is federal; the per-attempt fee around it is Idaho's own.
A federal bar, a cheap retake
49 CFR Part 383 sets the CDL general knowledge test at 50 questions and 80% nationwide, with Idaho's DMV administering that standard rather than writing its own.
Idaho's $3 written-test fee is genuinely low compared to some states, so a failed attempt doesn't carry a steep financial penalty — though it still costs time.
The bigger costs sit elsewhere in the process
The knowledge test fee is modest, but the $40 application fee and $70 skills test fee make up the bulk of Idaho's CDL cost.
Once you pass the knowledge test, the CLP holds for a full year — plenty of time to schedule the skills test after the mandatory 14-day wait.
The material that actually costs points
Air brake PSI thresholds and hours-of-service caps are memorization, not intuition — get the exact number wrong and the question is wrong, no partial credit for being close.
Cargo securement's 50-mile-then-150-mile recheck sequence is a common one to reverse under pressure.
A missed practice question is only useful if you read the full explanation — the correct letter alone teaches nothing.
Frequently Asked Questions
Can Idaho require a higher passing score than 80% for the CDL test?
No. 49 CFR Part 383 fixes the CDL general knowledge test at 50 questions and an 80% passing threshold nationwide — Idaho's DMV administers that federal standard rather than setting its own.
Does a failed knowledge test attempt cost extra to retake?
Yes, but only $3 per attempt — a comparatively low fee among the states covered here.
What score should I aim for on practice tests?
Aim for 90% or higher consistently before your appointment. That buffer above the 80% minimum accounts for first-attempt nerves.
Ready to put this into practice?
Start a free Idaho cdl practice testLast reviewed: 2026-07-23