What Happens If You Fail the C-36 Exam? Retake Rules, Wait Time and the 18-Month Deadline

If you fail the C-36 trade exam or the Law and Business exam, you can retake it after 21 calendar days, as long as you are not past your 18-month void date. You pay PSI each time you reschedule, and you only retake the exam you failed, because exam results are good for five years. The real limit is the 18 months your application gives you to pass. Miss that and the application is void, and you start over with a new application and new fees.

A failed exam is a speed bump, not a wall. The report you get on the way out tells you exactly where to aim the next three weeks.

Key facts

What your failing report tells you

You find out before you leave the test center. If you fail, the report shows your overall score, including the number of items answered correctly, and you see how well you did on each section of the exam.

Write those sections down before you walk out. CSLB says they correspond with the sections in the Content of the Examination on the study guide, which for the C-36 trade exam are:

A weak score in a big section costs more than a weak score in a small one. Start with the lowest score in the biggest section.

You cannot review the actual questions afterward. Test questions and answer keys are not available for review. If you think a question was wrong, CSLB has an appeal process: email your name and application number to exams@cslb.ca.gov and request an Examination Appeals Form.

The 21-day wait

Candidates who fail are eligible to retake the examination after 21 calendar days, as long as they are not past their 18-month void date. CSLB adds a warning worth reading twice: if you took your exam within three weeks of your void date, that was your last opportunity.

To rebook, you contact PSI through your PSI account or by phone, pay, and pick a new date.

You only retake the exam you failed

Exam results are good for five years. If you pass one exam and fail the other, you only have to retake and pass the one you failed. Your passed exam stays passed.

The deadline that actually matters

All applications are given 18 months from the day they are accepted to pass the exams. If you do not pass within 18 months, the application is considered void, and you will have to submit a new application with new fees. The application fee alone is $450, set by B&P Code section 7137.

So the expensive failure is not one retake. It is running out the clock.

Fees you can lose without failing

You also forfeit the exam fee if you:

• do not cancel your appointment 48 hours before the scheduled examination date,
• do not show up,
• arrive after the examination start time, or
• do not bring proper identification.

Common questions

Can you retake the C-36 exam if you fail?

Yes. You can retake it after 21 calendar days, as long as you are still inside the 18 months your application gives you to pass. You pay PSI each time you reschedule.

How long do you have to wait to retake the C-36 exam?

21 calendar days. If you took the exam within three weeks of your void date, CSLB says that was your last opportunity on that application.

Do I have to retake both exams if I fail one?

No. Exam results are good for five years, so you only retake the exam you failed.

Can I see the questions I got wrong?

No. Test questions and answer keys are not available for review. Your failing report shows your overall score and how you did on each section, which tells you what to study.

What happens if my 18 months run out?

The application is void, and you submit a new application with new fees, including the $450 application fee.

Sources

• CSLB Examinations Frequently Asked Questions
• CSLB, Get Licensed to Build
• CSLB License Examination Study Guide: Plumbing (C-36)
• California Business and Professions Code: Contractors State License Law

_Last reviewed: 2026-10-15. Every fact above is quoted from the CSLB document it cites and checked by code against our stored copy of that document._

Use the three weeks

Take the free 21-question C-36 diagnostic the day after a failed attempt. It shows you, topic by topic, where you would lose points today, so you can compare it with your failing report. No account needed. The full course is $148.75 one time: lessons for both exams, practice questions with written explanations, and timed practice exams, in English and Spanish. See what is included.