How to Verify a Contractor’s License in California Before You Hire (2026)

Before you hand $100,000 to $400,000 to an ADU contractor, you need to verify their contractor license in California — not ask them about it, not look at the plastic card they show you, but check it yourself in the CSLB database. It takes 30 seconds. The California Contractors State License Board maintains a free, public lookup tool at cslb.ca.gov that shows every licensed contractor’s status, bond, workers’ comp, classification, complaint history, and disciplinary record. This guide shows you exactly what to check and what each field means.

Every builder in the VerifiedADU directories for Sacramento, Los Angeles, and San Diego has already been verified against these records. But you should still know how to do it yourself — because not every contractor you encounter will be on our site, and blind trust is how homeowners get scammed.

Asking a contractor “Are you licensed?” is meaningless. The answer is always yes. Unlicensed contractors don’t tell you they’re unlicensed — they show you someone else’s license number, give you an expired number, or make one up entirely.

CSLB receives hundreds of complaints every year about unlicensed operators. Anchored Tiny Homes collected deposits from over 160 California homeowners before collapsing. Nonna Homes had its license suspended after a wave of complaints. Multitaskr took over $10 million from San Diego homeowners and delivered nothing. In every case, the homeowners who verified before hiring avoided the scam. The ones who trusted a business card did not.

Verification takes 30 seconds and costs nothing. There is no reason to skip it.

Step 1: Go to cslb.ca.gov

Step 2: Click “Check a License” (top of the page)

Step 3: Enter the contractor’s license number in the search field

Step 4: Click “Search”

Step 5: Review the detail page that appears

If you don’t have the license number, you can search by business name, owner name, or city. But searching by license number is the most reliable — name searches can return multiple results or miss contractors who operate under a DBA (doing business as) name.

Where to find the license number: Ask the contractor directly. It should also appear on their business card, website, proposal or bid document, and any contract they present. California law requires contractors to display their license number in all advertising. If a contractor can’t or won’t provide their license number, that’s your first red flag.

The CSLB license detail page shows several sections. Here’s what each one tells you and what you want to see:

License Status

This is the most important field. You’re looking for:

• “This license is current and active” — Good. The contractor is legally allowed to work.
• “Inactive” — The license is not current. The contractor cannot legally perform work. Do not hire.
• “Suspended” — CSLB has suspended the license due to bond lapse, insurance lapse, or disciplinary action. Do not hire.
• “Revoked” — The license has been permanently revoked due to serious violations. Do not hire under any circumstances.
• “Expired” — The license was not renewed. The contractor cannot legally work. They may be in the process of renewing, or they may have abandoned the business.

Only hire a contractor whose license shows “current and active.” No exceptions. Not “they said they’re renewing it.” Not “it expired last week.” Active means active.

Issue Date and Expiration Date

The issue date tells you how long the contractor has been licensed. A license issued in 2024 means 2 years of experience — not necessarily bad, but different from a contractor licensed since 2005. The expiration date tells you when the license needs to be renewed. If the expiration is approaching, the contractor should be in the renewal process.

Business Name and Personnel

Confirm the business name matches the company you’re talking to. The “Personnel” section shows the qualifying individual — the person whose experience and exam passage qualified the company for its license. If the qualifying individual leaves the company, the license can be affected.

California contractor licenses come in three main classifications. For ADU work, the classification matters.

Class	Name	Can Build an ADU?	Notes
B	General Building	Yes	The standard license for ADU construction. Can build the entire project.
A	General Engineering	Limited	Covers infrastructure — grading, paving, utilities. Not for building habitable structures.
C	Specialty	No (as GC)	C-10 (Electrical), C-36 (Plumbing), etc. Can perform specialty work but cannot serve as the general contractor for a full ADU build.

What you want: A contractor with a Class B (General Building) license. This is the classification that allows them to serve as the general contractor on an ADU project — managing all trades, pulling the building permit, and taking responsibility for the complete build.

A contractor with only Class A or Class C cannot legally serve as the general contractor on your ADU. They can do specialty work (electrical, plumbing, concrete) within their classification, but someone with a B license needs to be running the project.

Common confusion: Some contractors hold both A and B classifications. That’s fine — the B classification is what matters for ADU work. Having an A on top of a B is not a red flag; it just means they also do engineering work.

Contractor’s Bond ($25,000)

Every licensed California contractor must maintain a $25,000 surety bond. On the CSLB license detail page, look for the “Bonding Information” section:

• “This license filed a Contractor’s Bond with [COMPANY NAME]” — Good. The bond is active.
• No bond information — The bond has lapsed. The license should be suspended. Do not hire.
• “Bond cancelled” — The bonding company dropped the contractor. This usually means claims were filed or the contractor couldn’t pay the premium.

The bond protects you up to $25,000 if the contractor abandons the project, violates the contract, or commits fraud. It’s not enough to cover a full ADU project, but it’s a mandatory baseline of financial protection. For a detailed breakdown, read our surety bond guide.

Workers’ Compensation Insurance

The CSLB record shows workers’ comp status:

• “This license has workers compensation insurance with [COMPANY NAME]” — Good. Workers are covered.
• “This license is exempt from having workers compensation insurance” — The contractor is a sole proprietor with no employees. Legal under California law, but means they work alone or use subcontractors (who should have their own coverage).

If a contractor has employees and no workers’ comp insurance, you as the property owner can be held liable for injuries that occur on your property during construction. This is not theoretical — it happens, and the medical bills can be devastating.

General Liability Insurance

CSLB does not track general liability insurance. You have to ask the contractor for a certificate of insurance (COI) and verify it directly with the insurance company. GL insurance protects you if the contractor damages your property, a neighbor’s property, or causes injury to a third party during construction.

GL insurance is not required by California law, but any reputable contractor carries it. If a contractor refuses to provide a COI for general liability, find another contractor.

Here’s what to watch for on a CSLB record — any of these is a reason to walk away:

Red flag 1: License status is anything other than “current and active.”
Inactive, suspended, revoked, expired — none of these are acceptable. A contractor cannot legally perform work without an active license. Period.

Red flag 2: Bond cancelled or missing.
If the bonding section shows a cancelled bond or no bond at all, the contractor’s license should be suspended. If it’s not, the record may not have updated yet — but either way, no bond means no financial protection for you.

Red flag 3: Disciplinary action on record.
The CSLB record shows any formal disciplinary actions — citations, accusations, license restrictions. A single citation from years ago might be explainable. Multiple actions, recent actions, or a disciplinary bond requirement are serious warnings.

Red flag 4: Complaint disclosure.
CSLB shows complaint information when there are unresolved complaints or a pattern of complaints. Click the complaint disclosure link if it appears. Read the details. A contractor with active complaints is a contractor other homeowners are having problems with right now.

Red flag 5: License was recently issued and the contractor claims decades of experience.
If the license was issued in 2025 but the contractor claims 20 years in business, ask why. They may have operated under a different license that was revoked or surrendered. A new license on a company with “decades of experience” can mean the old license had problems.

Red flag 6: The license number doesn’t match the business name.
If the license the contractor gave you pulls up a different company name, something is wrong. They may be using someone else’s license, operating under an unregistered DBA, or deliberately misleading you.

California Business and Professions Code Section 7028 makes it a misdemeanor to perform contractor work without a license. But the legal consequences fall on the contractor — not you. Your consequences are financial:

• No bond protection. If the contractor abandons the project, there’s no surety bond to file a claim against.
• No CSLB complaint process. CSLB only investigates complaints against licensed contractors. An unlicensed contractor is outside their jurisdiction.
• No workers’ comp coverage. If a worker is injured on your property, you may be personally liable for medical bills and lost wages.
• Contract may be unenforceable. Under California law (B&P Code 7031), an unlicensed contractor cannot enforce a contract or collect payment through the courts. But this also means your contract with them has limited legal standing.
• Permit issues. An unlicensed contractor cannot pull a building permit. Any work done without a permit is a code violation that must be disclosed when you sell the property.
• Insurance void. Your homeowner’s insurance may not cover damage caused by unlicensed work.

The bottom line: hiring an unlicensed contractor for an ADU project is a six-figure gamble with no safety net. The 30 seconds it takes to check a license is the cheapest insurance you’ll ever get.

How do I verify a contractor’s license in California?

Go to cslb.ca.gov and enter the contractor’s license number. The detail page shows license status, classification, bond status, workers’ comp coverage, complaint history, and disciplinary actions. The lookup is free and takes 30 seconds.

What license does a contractor need to build an ADU?

A Class B (General Building) license is required for the general contractor on an ADU project. This classification allows them to build complete residential structures. Class A (General Engineering) and Class C (Specialty) contractors cannot serve as the general contractor on an ADU build.

What does “current and active” mean on a CSLB record?

It means the contractor’s license is valid, all required bonds and insurance are in place, and there are no suspensions or restrictions. This is the only status you should accept when hiring a contractor. Any other status — inactive, suspended, revoked, expired — means the contractor cannot legally perform work.

How do I check if a contractor is bonded in California?

The CSLB license detail page includes a “Bonding Information” section showing bond status, bonding company name, bond number, and effective date. Look for “This license filed a Contractor’s Bond with [company name].” If the bond section is empty or shows “cancelled,” the contractor is not properly bonded.

Can I verify a contractor’s insurance on CSLB?

CSLB shows workers’ compensation insurance status but does not track general liability insurance. To verify GL insurance, ask the contractor for a certificate of insurance (COI) and call the insurance company directly to confirm it’s current.

What happens if a contractor has complaints on their CSLB record?

CSLB discloses complaint information when there are unresolved complaints or a pattern of complaints. Click the disclosure link to read the details. A single resolved complaint from years ago may be acceptable. Multiple recent complaints, active investigations, or disciplinary actions are serious red flags.

Is it illegal to hire an unlicensed contractor in California?

It’s not illegal for you as the homeowner to hire an unlicensed contractor — the legal violation is on the contractor for operating without a license. However, hiring unlicensed means no bond protection, no CSLB complaint process, potential personal liability for worker injuries, and possible insurance voidance. The financial risks are severe.

How does VerifiedADU verify contractor licenses?

VerifiedADU checks every listed builder against CSLB public records for active license status, contractor bond on file, workers’ compensation insurance, and complaint history. This data is refreshed regularly. If a license status changes, the listing is updated or removed automatically.