What to verify before another trade works on your job, and what an uninsured sub does to your audit

Both of those land on you regardless of whose name is on the invoice.

“I’m solo, so I don’t carry comp” — what that actually means

This is the answer you will hear most often, and for a plumbing sub it is not automatically wrong. It is also not the same thing as a certificate, and the difference is worth understanding before you take it.

Business and Professions Code 7125(b)(1) lets a licensee with no employees be issued or renewed without a comp certificate — but only where that licensee "files a statement with the board on a form prescribed by the registrar … certifying that the applicant or licensee does not employ any person" in a way that brings them under California workers' compensation law. So there are three possibilities behind the sentence he just said to you, not one: he filed the exemption and it is accurate; he filed it and it stopped being accurate; or he never filed anything at all. Those are three different risks. You can tell them apart in about ninety seconds on cslb.ca.gov.

Three more things that turn a valid-sounding exemption into no exemption:

• A second classification. Section 7125(b)(2) takes the exemption away from any licensee holding C-8, C-20, C-22, C-39 or D-49. A plumbing sub who also carries C-20 for HVAC crossover has no exemption available, whatever his headcount.
• A hire he made last month. Per CSLB, employing anyone subject to California workers' compensation law invalidates a filed exemption immediately, with proof of coverage due to CSLB within 90 days. The helper he brought on for your repipe may be the hire that did it.
• The calendar. Section 7125 repeals itself on January 1, 2028, and the version that replaces it keeps the no-employee exemption only for joint ventures. What changes in 2028 is here.

And the plain one: an exemption is a licensing status, not coverage. If your sub gets hurt on your job, there is no comp policy standing behind him. That is a different conversation from a sub who simply has nothing — but it is not the same conversation as a sub who hands you a certificate.

Suspension happens by itself

BPC 7125.2 says failure to obtain or maintain required coverage "shall result in the automatic suspension of the license by operation of law," effective on the earlier of the date coverage lapsed or the date it became required. The same section then requires the registrar to give written notice of the reason, the effective date and the procedure to reinstate. CSLB adds that work done while suspended "is considered to be unlicensed." Because it backdates, the status you pulled when you bid in June says nothing about the morning his crew showed up.

What to actually check

• License number, every classification on it, and status on cslb.ca.gov, the week they start. Not at bid, and not from a screenshot they sent.
• The comp certificate, sent to you by their broker directly. A PDF forwarded by the sub is a PDF.
• If they claim the exemption, what CSLB actually shows. The license record is where a filed exemption lives. “I’m solo” is not a filing, and a filing is not coverage.
• If they claim self-insurance, the actual Certification of Self-Insurance. A policy number typed onto a permit form is not it.
• Their general liability, with the endorsements — not just the certificate. Water finds finished walls and finished floors, and completed-operations coverage is where those claims land.
• All of it again on any job running past a renewal date. Certs and exemptions both go stale quietly.

What a certificate is

Read the top of the ACORD 25 they hand you. In caps: "THIS CERTIFICATE IS ISSUED AS A MATTER OF INFORMATION ONLY AND CONFERS NO RIGHTS UPON THE CERTIFICATE HOLDER." The cancellation box says notice "will be delivered in accordance with the policy provisions," so nothing on that page obligates anyone to call you when the policy goes away. A cert is a snapshot and proof you asked. Treat it as both, and re-pull.

What your audit does with it

The mechanic that catches people sits in the standard comp policy form (NCCI WC 00 00 00 C, Part Five, Section C). It puts into the premium basis "all other persons engaged in work that could make us liable under Part One," then continues: "If you do not have payroll records for these persons, the contract price for their services and materials may be used as the premium basis. This paragraph 2 will not apply if you give us proof that the employers of these persons lawfully secured their workers compensation obligations."

Read that last sentence twice. The way out is proof. Without it, what you paid the sub can land in your payroll basis. The form never defines what "proof" looks like, and it does not say whether a CSLB exemption filing counts as evidence that a sub "lawfully secured" his obligations. Ask your carrier what they accept, in writing, before the job — not after the auditor asks who the check went to.

General liability runs a parallel track. Per the Independent Insurance Agents & Brokers of America’s summary of the ISO manual rule, an uninsured or inadequately insured sub gets charged on payroll under the class fitting his work instead of on total contract cost. And Insurance Code 676.8 lists failure to permit an audit, or to pay additional premium from one, as grounds to cancel a comp policy on 10 days' written notice. The same section says the policy is not canceled if the condition is remedied to the insurer’s satisfaction inside that notice period, which is the whole reason to open the letter.

The license side runs alongside it

Labor Code 2750.5 says any person doing work requiring a contractor’s license "shall hold a valid contractors' license as a condition of having independent contractor status," and carries a rebuttable presumption that the worker is an employee. BPC 7118 makes contracting with an unlicensed contractor a cause for disciplinary action against the licensee who hired them. BPC 7031(b) lets whoever paid an unlicensed contractor sue to recover all compensation paid.

How that lands on a given job is a lawyer’s question. It all keys off one fact you can check in ninety seconds.

Do this today

Pull the last three subs you used. Check each license number on cslb.ca.gov, read every classification listed and the workers' compensation line — not just the word "Active" — and email the broker on anything you can’t verify. Where the record shows an exemption rather than a certificate, decide deliberately whether that is acceptable on the kind of work you hand that sub. Then move the whole check into whatever you use to open a job.

To see what your own license class has to carry, run the requirements checker. Aster is an independent commercial insurance brokerage and places coverage with carriers, so that is who you would be dealing with if you go past the lookup.

Aster National Insurance Group, Duarte CA. CA Lic #0N10039. General information only, not legal advice and not a coverage determination. Any coverage depends on the terms of the policy issued. Statutes cited are current as of August 2026; check the current text at leginfo.legislature.ca.gov and cslb.ca.gov.