A drywall foreman gets his Notice to Schedule in the mail from the Contractors State License Board. He has two exams to book: the C-9 trade exam and Law and Business. He has hung board for years. What he does not know is what the test will look like, how long he gets, what he can bring, or what happens if he fails one.
Here is the plain answer. The CSLB exam is usually two separate computer-based, multiple-choice exams taken in person at a PSI site: a trade exam for your classification and the Law and Business exam. You get 3-1/2 hours for each. Both are closed book. CSLB publishes the topics and how much each is weighted, but it does not publish a passing percentage. If you fail, you can retake after 21 calendar days, as long as you are still inside the 18 months you have to pass.
Below is what each exam covers, what test day looks like, and how to study for both.
The basics in one list
From CSLB’s Examination FAQ and its study guides:
- Scheduling: after CSLB refers you for testing, you book and pay for each exam directly with PSI. Each exam has its own fee.
- Order: take them on the same day or at different times. Your choice.
- Time: 3-1/2 hours per exam.
- Format: multiple choice on a computer. Four choices per question, one BEST answer.
- Books: closed book. A calculator is provided.
- Guessing: no penalty. Answer every question.
- Where: trade exams in California or Oregon. Law and Business can also be taken out of state.
- Retake: after 21 calendar days.
- Deadline: 18 months from when your application was accepted.
What CSLB does not publish
CSLB does not publish a passing percentage or the number of scored questions for its exams. You may see a passing percentage or a question count quoted online. Those numbers do not come from CSLB.
What you get instead is a score report. If you fail, the report shows your overall score, the number you got right, and how you did by section. If you pass, it does not show a score at all. Our post on how CSLB exam scoring works explains what that means for how you practice.
The trade exam
Each classification has its own trade exam and its own study guide. The guide lists the sections, what each covers, and roughly how much of the exam each one is.
Example: B General Building
CSLB’s B study guide, for exams on or after January 1, 2025, splits the exam into five sections:
- Planning and Estimating: about 15%.
- Framing and Structural Components: about 20%.
- Core Trades: about 30%.
- Finish Trades: about 20%.
- Safety: about 15%.
Other trades are split differently. The C-10 Electrical guide, for example, puts more weight on planning and rough wiring than on finish work. Always use the guide for your own classification, and check its effective date.
Closed book means memory
CSLB’s study guides say the exams are closed book, with no reference materials allowed. That changes how you study. You cannot look up a code table during the test. You need to know the common values, the common methods, and the safety rules well enough to recall them.
The Law and Business exam
This exam is the same for every classification that has to take it. CSLB’s Law and Business study guide divides it into seven sections:
- Business Organization and Licensing: about 13%.
- Business Finances: about 15%.
- Employment Requirements: about 20%.
- Insurance and Liens: about 12%.
- Contract Requirements and Execution: about 21%.
- Public Works: about 5%.
- Safety: about 14%.
Contracts and employment together are about four questions in ten. That is where to start. Our post on the most tested Law and Business topics goes through each section and the rules that come up most.
Many tradespeople put all their time into the trade exam and treat Law and Business as an afterthought. It is a separate exam with its own result. Failing it holds up the license just as much.
Test day at PSI
- ID: bring one valid, non-expired, government-issued ID from CSLB’s list, such as a driver’s license, state ID card or passport.
- Leave it in the car: phones, smart devices, calculators, notes, books, food, drinks, hats and bulky jewelry are among the items not allowed in the testing room. PSI provides the calculator.
- Arrive on time. Arriving after the start time forfeits your exam fee.
- Cancel early if you must. You keep your fee if PSI receives your cancellation 48 hours before the appointment.
The exams are in English. CSLB also offers Spanish versions of several common exams, including Law and Business and B General Building, and allows approved translators under strict rules.
How to study for both
Start with the study guide
Print the guide for your trade and the Law and Business guide. Use the section weights to split your time. A section worth a fifth of the exam deserves about a fifth of your study.
Practice under the clock
Take full-length timed practice exams. You learn your pace, and you find out which sections cost you the most points.
Review every miss
For each question you miss, find the rule and write it down in your own words. Patterns show up fast.
Do the math by hand
Both guides say some questions require calculation. Practice with a basic calculator so the one PSI gives you feels familiar.
Answer everything
There is no penalty for guessing. Never leave a question blank.
Want to try a few first? Start with our free CSLB practice questions.
Trade or Law and Business first?
Either order works. Some candidates take the one they feel strongest on first, to get a pass in hand. Others take both on one day to finish in a single trip. Our comparison of the trade exam and the Law and Business exam lays out the tradeoffs.
If you fail
It happens. CSLB lets you retake after 21 calendar days, as long as you are not past your 18-month void date. You pay a re-examination fee to PSI.
- Read your score report. It shows how you did by section.
- Go back to the weakest sections in the study guide first.
- Book the retake with enough time to study, but well inside your 18 months.
If you take an exam within three weeks of your void date and fail, CSLB says that was your last chance on that application.
After you pass
CSLB sends a bond and fee letter listing what to file before the license is issued: the initial license fee, a $25,000 contractor bond, workers’ compensation or an exemption, the asbestos open-book exam, and anything else that applies to your business.
Questions candidates ask
Are any CSLB exams open book?
The trade and Law and Business study guides say closed book. The asbestos exam you complete before licensing is open book, but that is a separate step, not one of your PSI exams.
How long should I study?
It depends on your experience and how you do on practice exams. Use your practice scores by section to decide when you are ready.
Can I review the questions I got wrong?
No. CSLB does not let candidates review exam questions or answer keys. Your score report is the feedback you get.
Next step
Pick your classification on our California contractor exam prep page. Each course follows CSLB’s study guide for that exam, with full-length timed practice exams for the trade and for Law and Business.