An electrician with years of panel work behind them opens the C-10 study guide and relaxes. Grounding, raceways, load calculations, lockout/tagout. They know this. Then they open the Law and Business study guide. Payroll deposits, mechanics liens, prevailing wage, workers’ compensation certificates. Same board, same testing center, completely different exam.
Here is the plain answer. Most CSLB applicants take two exams: a trade exam for their classification and the Law and Business exam. Both are closed book, multiple choice, and three and a half hours long. The trade exam tests what you do on the job, in your classification. Law and Business tests how you run a contracting business in California, and it is the same exam for every classification. They feel different because they reward different kinds of studying: the trade exam rewards experience plus code, and Law and Business rewards memorizing rules, deadlines and procedures.
This post compares the two side by side and lays out how to study for each.
Side by side
Trade exam
- What it covers: Your classification’s work, from planning and estimating through installation, troubleshooting and safety.
- Who takes it: Everyone sitting that classification. Each classification has its own exam and its own study guide.
- Format: Computer-based, multiple choice, four choices per question, one BEST answer.
- Time: Three and a half hours.
- Books: Closed book. The study guide lists reference books to study from, but none are allowed in the room.
- Where: CSLB’s FAQ says trade exams are given only in California and Oregon.
Law and Business exam
- What it covers: Seven sections: business organization and licensing, business finances, employment, insurance and liens, contracts, public works, and safety.
- Who takes it: Applicants for every classification take the same exam, unless CSLB waives it for them.
- Format: Computer-based, multiple choice, four choices per question, one BEST answer.
- Time: Three and a half hours.
- Books: Closed book.
- Where: California test centers, plus PSI centers in a list of other states.
The format, time and test-center facts above come from CSLB’s Examination FAQ and its study guides. CSLB does not publish a passing percentage for either exam, so we do not print one. Our post on how CSLB exam scoring works explains what the board does publish.
How the content differs
The trade exam follows your classification
Every trade exam has its own sections and weights. The C-10 Electrical study guide is a good example. For exams on or after June 1, 2024, CSLB’s C-10 study guide lists five sections:
- Planning and Estimating: 28%
- Rough Wiring: 27%
- Finish Wiring and Trim: 11%
- Startup, Troubleshooting, and Maintenance: 16%
- Safety: 18%
Other classifications split differently. Planning and estimating and safety show up in nearly all of them. The middle sections follow the work itself. Download the study guide for your classification and check the date at the top, because guides are revised.
Experience helps here, but it is not enough by itself. Questions are tied to California codes and standards, and some require calculations. A calculator is provided. Field habits that work but do not match code will cost you points.
Law and Business is the same for everyone
CSLB’s Law and Business study guide lists these sections and approximate weights:
- Contract Requirements and Execution: 21%
- Employment Requirements: 20%
- Business Finances: 15%
- Safety: 14%
- Business Organization and Licensing: 13%
- Insurance and Liens: 12%
- Public Works: 5%
Very little of this comes from the field. A plumber with decades of experience may never have filed a workers’ compensation certificate, written a home improvement contract to the letter of the law, or tracked a lien deadline. That is why experienced tradespeople sometimes pass the trade exam and fail Law and Business. Our post on the most tested Law and Business topics walks through each section.
Which one to take first
CSLB’s FAQ says each exam has its own fee and can be scheduled on the same day or at different times. So the order is your choice. Here is how to think about it.
- Trade first. Fits when you are strong in the field and want a win that builds momentum. Does not fit when your trade exam needs heavy code study and Law and Business is the easier lift for you.
- Law and Business first. Fits when you have business or office experience, or when you want the less familiar exam done while your study energy is high. Does not fit when you have not started on the reference material at all.
- Same day. Fits when travel to a test center is hard and you are ready for both. Does not fit when either exam still feels shaky. Seven hours of testing in one day is tiring.
Whatever order you choose, keep the 18-month clock in mind. CSLB gives you 18 months from the date your application is accepted to pass your exams. If you do not, the application is void and you start over with new fees.
If you fail one
You retake only the exam you failed. CSLB’s FAQ says candidates who fail can retake after 21 calendar days, as long as they are not past the 18-month void date. Each retake needs a re-examination fee paid to PSI.
If you fail, the score report shows your overall score and a breakdown by section. Use it. Line up the weak sections against the study guide and spend your next three weeks there.
How to study for each
For the trade exam
- Start with the study guide sections. Rank them by weight and by how comfortable you are.
- Study the codes behind your work. California’s versions, not just what you do on site.
- Practice the math. Load calculations, volumes, slopes, conversions, whatever your trade uses.
- Do not skip safety. It is a full section on most trade exams.
For Law and Business
- Memorize the numbers that are rules. Contract thresholds, down payment limits, notice periods and lien deadlines.
- Learn processes as timelines. Preliminary notice, completion, notice of completion, lien deadline, release.
- Use the reference book while studying. The study guide lists the California Contractors License Law and Reference Book and the California Employer’s Guide.
- Take timed practice exams. Closed book, three and a half hours, so the real day feels familiar.
For a week-by-week plan that covers both, see our CSLB exam study plan.
Where candidates go wrong on each
On the trade exam
- Answering from habit instead of code. The way your crew has always done it may not be the answer the code supports.
- Skipping planning and estimating. It is often one of the heaviest sections, and field workers who never bid a job find it unfamiliar.
- Missing the capitalized word. MINIMUM, MAXIMUM, MOST and BEST change which choice is right.
On Law and Business
- Treating it as common sense. Many questions have one exact answer, such as a number of days or a dollar limit. Close is wrong.
- Mixing up similar deadlines. Lien and notice periods look alike. Learn them in order, not as a list.
- Underestimating employment and payroll. It is one of the two largest sections, and it is the least familiar to most tradespeople.
Questions candidates ask
Can I bring code books to the trade exam?
No. CSLB’s study guides describe the trade exams as closed book. No reference materials may be used during the exam.
Can I take the exams in Spanish?
For some. CSLB’s FAQ lists Spanish versions of several common exams, including Law and Business, B General Building, C-36 Plumbing and others. For other exams, CSLB may approve a translator in advance.
Do I always have to take Law and Business?
Most applicants do. Some qualify for a waiver. Your Notice to Schedule from CSLB lists the exams your application requires.
Next step
Find your classification on our California exam prep page. Each course has a study guide and full-length practice exams built from that classification’s CSLB study guide, and Law and Business has its own course.