- Every KY-CDL knowledge test - from General Knowledge to School Bus - requires an 80% score to pass.
- The General Knowledge Test has 50 questions; most endorsement tests have 20-30.
- The standard one-year permit costs $11 ($14 with REAL ID), plus a $3 NCIC fee.
- Failed tests trigger a 24-hour wait; retests for Combination Vehicles, Air Brakes, and endorsements cost $5.
Quick Facts Snapshot
If you only have five minutes before you walk into the Kentucky State Police testing location, this is the section to read. The Kentucky Transportation Cabinet issues the credential, but Kentucky State Police is the agency that actually administers your knowledge, vision, and skills tests. All questions on the current cheat sheet are pulled from the March 2025 manual, so if you're studying from an older PDF you found online, toss it - Kentucky updates content periodically and outdated material can cost you points on questions that changed wording or emphasis.
For a deeper breakdown of every rule referenced here, the KY-CDL Requirements 2026: Eligibility, Prerequisites & How to Qualify guide covers eligibility in full, and the KY-CDL Certification Cost 2026: Complete Pricing Breakdown article breaks down every fee line item.
The 8 Test Domains at a Glance
Kentucky's CDL knowledge testing is split into eight distinct tests, each with its own question count and its own 80% passing threshold. Not every candidate takes all eight - it depends on the class of license and endorsements you're pursuing. Here's the exact lineup:
| Domain | Question Count | Passing Score |
|---|---|---|
| General Knowledge | 50 | 80% |
| Combination Vehicles | 20 | 80% |
| Air Brakes | 25 | 80% |
| Hazardous Materials | 30 | 80% |
| Doubles/Triples | 20 | 80% |
| Tankers | 20 | 80% |
| Passenger Transport | 20 | 80% |
| School Bus | 20 | 80% |
Notice the pattern: General Knowledge is the biggest test by far, and Hazardous Materials is the biggest endorsement test. If you're only chasing a Class A with no endorsements, you'll likely only face General Knowledge, Combination Vehicles, and possibly Air Brakes. For a full walkthrough of what's actually tested inside each of these eight areas, see KY-CDL Exam Domains 2026: Complete Guide to All 8 Content Areas.
General Knowledge Test
This is the foundation everyone takes. It covers driving safety, vehicle inspection basics, and general rules that apply regardless of what you'll eventually haul or drive.
- 50 questions, 80% required - that's 40 correct answers minimum
Combination Vehicles Test
Required for anyone pursuing a Class A license. Focuses on coupling, uncoupling, and handling multi-unit vehicles safely.
- Only 20 questions, but 80% still means missing no more than 4
Air Brakes Test
Mandatory if your vehicle is equipped with air brakes - which most commercial trucks are. Skipping this test restricts your CDL with an air brake restriction.
- 25 questions; written or oral format available
Hazardous Materials Test
The largest endorsement test at 30 questions, and the only one with no oral testing option. This endorsement also requires additional background checks beyond the knowledge test itself.
- 30 questions, written format only
Passing Score and Retest Rules
There's no sliding scale in Kentucky - every single knowledge test, from General Knowledge down to School Bus, uses the same 80% cutoff. That consistency actually makes planning easier: whatever domain you're studying, your target is identical. For the full logic behind why 80% was chosen and how it compares elsewhere, read KY-CDL Passing Score 2026: Exactly What You Need to Pass.
Key Takeaway
If you fail any knowledge test, you must wait 24 hours before retesting. After your first failed attempt, retests for Combination Vehicles, Air Brakes, and endorsement tests carry a $5 fee - so treat your first attempt as the one that counts.
This retest structure rewards preparation over guessing. A candidate who walks in unprepared and fails General Knowledge loses a full day before they can try again, and if they're also retesting an endorsement, the $5 fees start adding up test by test. Compare this against candidates who slow down and study first - the math almost always favors preparation. For candid discussion of where most people actually struggle, see How Hard Is the KY-CDL Exam? Complete Difficulty Guide 2026 and KY-CDL Pass Rate 2026: What the Data Shows.
Fees and Costs Cheat Sheet
Kentucky's fee structure is layered - a base permit fee, an NCIC background check fee, and then an add-on fee for the actual CDL once you've passed your skills test. Here's every number in one place:
| Item | Cost |
|---|---|
| Standard 1-year commercial permit | $11 |
| Commercial permit with REAL ID | $14 |
| NCIC background check fee | $3 |
| Original CDL add-on | $18.75-$50 (varies by credential type and time remaining) |
| Retest fee (Combination Vehicles, Air Brakes, endorsements, after first fail) | $5 |
The wide range on the CDL add-on fee ($18.75 to $50) surprises a lot of candidates. It depends on your credential type and how much time is left before renewal - not something you can control much, but worth budgeting for on the high end so you're not caught short. A full pricing breakdown, including how these fees stack for different license classes, lives at KY-CDL Certification Cost 2026: Complete Pricing Breakdown.
Eligibility Checklist
Before you even schedule a test, confirm you meet Kentucky's baseline requirements. Missing one of these can stall your entire timeline:
- Minimum age 18 for intrastate driving, 21 for interstate driving
- Hold a valid, unexpired driver license
- Meet current medical certification standards
- Complete self-certification of your driving category
- Complete applicable Entry-Level Driver Training (ELDT) before testing
- Hold your Commercial Learner's Permit (CLP) for a minimum of 14 days before taking the skills test
That 14-day holding period trips people up more than almost anything else on this list. Even if you pass every knowledge test on day one, you cannot schedule your skills test until two full weeks have passed since your permit was issued. Plan your skills test date backward from your permit issue date, not the other way around. The complete eligibility breakdown, including ELDT specifics, is covered in KY-CDL Requirements 2026: Eligibility, Prerequisites & How to Qualify.
What to Study First
Not all eight domains deserve equal study time. Prioritize based on two factors: which tests you're actually required to take, and which ones carry the most questions relative to their difficulty. Here's a sensible order for most Class A candidates pursuing a standard combination endorsement path:
- General Knowledge - largest test, foundational vocabulary for everything else
- Air Brakes - required for most vehicles, moderate length at 25 questions
- Combination Vehicles - shorter test but technical content on coupling/uncoupling
- Endorsement tests relevant to your job target - Tankers, Doubles/Triples, Passenger Transport, School Bus, or Hazardous Materials, depending on the driving work you want
If you're unsure which endorsements actually matter for your career goals, look at what regional carriers are hiring for before you commit study hours to an endorsement you may never use. The KY-CDL Jobs resource is a useful reality check here, and pairing that with KY-CDL Salary Guide 2026: Complete Earnings Analysis helps you weigh whether an extra endorsement is worth the study time and the $5 retest exposure if you fail it.
Key Takeaway
Study General Knowledge and Air Brakes first - they're required by nearly everyone and form the vocabulary base for every other domain. Add endorsement-specific tests only once those two are solid.
One-Week Refresher Schedule
If you already have a driving background and just need a structured final push, a compressed one-week schedule tied to the actual domain weights works better than generic daily quizzing. Here's how to sequence it:
General Knowledge
- Work through all 50-question content areas; this is the biggest test and the base for the rest
- Review manual sections tied to inspection and safe driving practices
Air Brakes and Combination Vehicles
- Air Brakes: focus on system components and warning procedures (25 questions)
- Combination Vehicles: focus on coupling/uncoupling sequences (20 questions)
Your Target Endorsement
- Choose one of Tankers, Doubles/Triples, Passenger Transport, School Bus, or Hazardous Materials based on job goals
- If it's Hazardous Materials, remember there's no oral option - practice written-format recall specifically
Full Review and Rest
- Run through weak areas identified in earlier practice sessions
- Confirm your permit has been held long enough to satisfy the 14-day skills test rule
This sequencing matters more than any generic study trick. For a longer, more detailed version of this approach with additional review methods, see KY-CDL Study Guide 2026: How to Pass on Your First Attempt. You can also run timed practice sets on our practice test platform to simulate the real question format before test day.
Day-of-Test Reminders
A few operational details often get overlooked in the rush to study content:
- Confirm whether you're taking the written or oral format ahead of time - remember, Hazardous Materials has no oral option
- Bring your valid driver license and any documentation required for the NCIC background check
- If retesting after a failure, budget the $5 fee and remember the mandatory 24-hour wait
- Double-check your CLP issue date against the 14-day minimum if you're scheduling a skills test
Once you're past the knowledge tests, the skills test is the final gate, and it can only happen after your 14-day CLP hold. Use that waiting period productively - it's a good window for a final review pass rather than idle time. For a broader look at whether the full certification path pays off for your career plans, see Is the KY-CDL Certification Worth It? Complete ROI Analysis 2026, and for scheduling logistics around testing windows, check KY-CDL Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Frequently Asked Questions
Every knowledge test - General Knowledge, Combination Vehicles, Air Brakes, Hazardous Materials, Doubles/Triples, Tankers, Passenger Transport, and School Bus - requires 80%.
No. Every knowledge test in Kentucky can be taken written or oral except Hazardous Materials, which is written only.
You must wait 24 hours before retesting. Combination Vehicles, Air Brakes, and endorsement retests cost $5 after your first failed attempt.
You must hold your Commercial Learner's Permit (CLP) for at least 14 days before you're eligible to take the skills test.
Yes. The standard one-year commercial permit is $11, but it's $14 if tied to a REAL ID, plus a separate $3 NCIC background check fee.