Washington plumbing license requirements and insurance

To work for yourself as a plumber in Washington, you need the Plumbing Contractor License license. Washington has 6 plumbing license types, and which one you need depends on the work you take on. The state's minimum liability insurance is $200,000 for injury and $50,000 for property damage, and workers' comp is required once you have employees. A $6,000 bond is required.

Checked by the Trades by State editor on 2026-09-06 Based on 25 official pages, listed at the bottom Something wrong? Tell us

License you need: Plumbing Contractor License Renew Every 2 years (the license expires 24 months after it is issued)
Insurance you must carry: $200,000 plus $50,000 for property damage
Workers' comp: Required as soon as you hire anyone
Credit score: None or take a 14-hour course
To protect your pay, send notice by: Send it early. The notice only protects work done in the 60 days before you send it, so anything older is lost (work started on March 1 and notice sent on June 1 covers only work from April 2 onward). On a new single-family house it covers only the 10 days before the notice

Turn this into a checklist

1 What stands out in Washington for a plumber What is this?

The things people get wrong or do not expect about Washington, in a few sentences.

Washington charges sales tax on your labor. On a normal job for a customer you collect retail sales tax on the whole bill, labor and materials, and buy the materials tax-free with a reseller permit. The rule is the same for a house and for a business.
A plumbing business needs a plumbing contractor license from L&I, with a $6,000 bond. That is separate from the general contractor registration, which now needs a $30,000 bond. If you only do plumbing you need only the plumbing license.
Journey level takes 8,000 hours, about four years, and the state expects half of it on commercial or industrial work. Residential takes 6,000 hours and residential service 4,000 hours.
Plumber cards run three years and cost $242.70 to renew. You need 24 hours of classes in that time, and four of those hours must be about electrical safety.
Workers' comp comes only from the L&I state fund. You cannot buy a private policy. You need an account as soon as you hire one employee.
On any job of $1,000 or more you must hand the customer a written disclosure statement before you start. If you skip it you cannot file a lien on that job.

Checked by a person against the official page

·7 official pages

2 Who issues plumber licenses in Washington? What is this?

Washington State Department of Labor and Industries (L&I), Plumber Certification Program and Contractor Registration issues plumbing licenses in Washington.

Name	Washington State Department of Labor and Industries (L&I), Plumber Certification Program and Contractor Registration
Website	https://lni.wa.gov/licensing-permits/plumbing/
Look up a license	https://secure.lni.wa.gov/verify/
The law	RCW chapter 18.106 (plumbers and plumbing contractors) and RCW chapter 18.27 (contractor registration)
The rulebook	WAC chapter 296-400A (plumbers) and WAC chapter 296-200A (contractor registration)

Checked by a person against the official page

3 Washington plumber license requirements and fees What is this?

Washington has 6 license types that matter to a plumber. The Plumbing Contractor License needs none for the business itself. You must employ, full time, one person who holds a journey level or specialty plumber card and name that person to L&I as your designated plumber.

Plumbing Contractor License

Any business that does, offers, or advertises plumbing work. This is the license that lets you run a plumbing company

What you can work on

Plumbing work as defined in RCW 18.106, meaning water, drain, waste, vent, and medical gas piping inside buildings. Natural gas piping is not covered by this definition

Experience required

None for the business itself. You must employ, full time, one person who holds a journey level or specialty plumber card and name that person to L&I as your designated plumber

Training required

None

Exam

Fees

Application	$148.1
Naming your designated plumber	53.2
Renewal	$139.1

Renewal

Every 2 years (the license expires 24 months after it is issued)

Training hours each year

Taken from the linked page, not separately checked

·4 official pages

Journey Level Plumber (PL01)

The card that lets you do any plumbing work and supervise trainees. Most businesses name a journey level plumber as their designated plumber

What you can work on

All plumbing work, residential and commercial

Experience required

8,000 hours (four years or more) as a plumber trainee under a certified journey level plumber. L&I expects at least 4,000 of those hours on commercial or industrial work

Training required

None required beyond the trainee's yearly classes. An approved apprenticeship or trade course can count toward the hours

Exam

Yes, an L&I exam run by PSI at PSI test centers. Closed book

Fees

Exam application	$202.1
Booking the exam (PSI)	Not listed yet
First license	$242.7
Renewal	$242.7
Late renewal	Double the renewal fee. After 90 days you must retest
Retest after a lapse	$189.8

Renewal

Every 3 years, on your birthday

Training hours each renewal

About training hours

At least 12 hours on the plumbing code and at least 4 hours on industry-related electrical safety. The other 8 can be any approved plumbing or electrical class

Taken from the linked page, not separately checked

·6 official pages

Residential Plumber (PL02)

Lets you do plumbing in houses and other residential buildings up to three stories. A business can use a residential plumber as its designated plumber

What you can work on

Residential buildings up to three stories

Experience required

6,000 hours (three years or more) as a plumber trainee under a certified plumber

Training required

None beyond the trainee's yearly classes

Exam

Yes, an L&I exam run by PSI. Closed book

Fees

Exam application	$202.1
First license	$242.7
Renewal	$242.7

Renewal

Every 3 years, on your birthday

Training hours each renewal

Checked by a person against the official page

·3 official pages

Residential Service Plumber (PL04)

Lets you repair and replace existing fixtures in single-family homes and duplexes, clean drains, and fix leaks. Not new installs

What you can work on

Service, repair, and replacement of existing plumbing in single-family homes and duplexes

Experience required

4,000 hours (two years or more) as a trainee under a journey level, specialty, or residential service plumber

Training required

None beyond the trainee's yearly classes

Exam

Yes, an L&I exam run by PSI

Fees

Exam application	$202.1
First license	$242.7
Renewal	$242.7

Renewal

Every 3 years

Training hours each renewal

Checked by a person against the official page

·3 official pages

Plumber Trainee

Everyone learning the trade. You cannot touch plumbing work in Washington without a trainee card or a plumber card, plus photo ID on you

What you can work on

Any plumbing work, under the direct supervision of a certified plumber

Experience required

None. Be 16 or older

Training required

8 hours of approved classes each year to renew. Over two years that must include 8 hours of plumbing code and 4 hours of electrical safety

Exam

Fees

First license	60
Renewal	60

Renewal

Annual (the card lasts 12 months). File your affidavit of experience, the form that reports your supervised hours, at least once a year and within 30 days of your renewal date

Training hours each year

Checked by a person against the official page

·2 official pages

Other plumber specialties (pump and irrigation PL03, domestic well PL03A, backflow PL30, medical gas endorsement MG01)

Niche cards. Pump and irrigation needs 4,000 hours, domestic well 2,000 hours, backflow needs an active backflow assembly tester certificate, and medical gas needs a 32-hour approved course on top of a plumber card

Fees

Exam application	$202.1
Medical gas add-on, application	74.3
Pump certificate	$242.8
Backflow certificate	$167.4
Medical gas certificate	$166.9

Renewal

Every 3 years

Checked by a person against the official page

·2 official pages

4 How much insurance does a plumber need in Washington? What is this?

The least liability insurance Washington lets a plumber work with is $200,000 for injury and $50,000 for property damage. Most customers ask for more. Workers' comp is required once you have employees.

Minimum liability insurance (injury)	$200,000
Minimum liability insurance (property damage)	$50,000
Or one combined limit of	$250,000
Type of policy	General liability insurance
Who this applies to	The plumbing contractor license holder, meaning the business. The statute writes it as $100,000 for one person, $200,000 for more than one person, and $50,000 property damage
Who must be named on the certificate	File the insurance certificate with L&I. If the policy lapses or is canceled, the license is suspended until a new policy is filed
Workers' comp required?	Yes, as soon as you hire one employee. Coverage comes only from the L&I state fund. Private workers' comp policies are not allowed in Washington
Who can opt out	Sole proprietors, partners, LLC members, and corporate officers who own shares, sit on the board, and run the business day to day are excluded. A private company can also exclude up to eight officers. Any of them can buy optional coverage from L&I

Checked by a person against the official page

·5 official pages

5 Does Washington check your credit for a plumber license? What is this?

Washington does not check your credit for this license.

Credit score you need	None
If your score is lower	Instead of a surety bond you can file an assigned savings account with L&I for the same amount

Checked by a person against the official page·app.leg.wa.gov

6 Does a plumber need a bond in Washington? What is this?

Washington requires a bond of $6,000. A bond is a promise, backed by an insurance company, that customers can be paid if you do not finish the job.

Does the state require a bond?	Yes
Amount	$6,000

A continuous plumbing contractor surety bond (a promise, backed by an insurance company, that customers can be paid if you do not finish or do bad work) of $6,000, or an assigned savings account instead. This is for the plumbing contractor license only. If you also do non-plumbing construction you need a separate contractor registration under RCW 18.27 with its own bond, $30,000 for a general contractor or $15,000 for a specialty contractor. Cities may ask for more before they let you pull permits

Checked by a person against the official page

·3 official pages

7 Where must a Washington plumber show the license number? What is this?

In Washington: if you hold a contractor registration under RCW 18.27, every ad that shows your name or address must show your registration number, and so must every flyer or mailer sent to homeowners. Vehicle signs and signs on your own building are exempt. For a plumbing contractor license under RCW 18.106 the state's pages give no number-display rule, so check WAC 296-400A before printing.

The rule	If you hold a contractor registration under RCW 18.27, every ad that shows your name or address must show your registration number, and so must every flyer or mailer sent to homeowners. Vehicle signs and signs on your own building are exempt. For a plumbing contractor license under RCW 18.106 the state's pages give no number-display rule, so check WAC 296-400A before printing
If you forget	Up to $10,000 per violation after a hearing. Not charged for an honest mistake
Written notice you must give the customer	Before starting any home job of $1,000 or more, or a commercial job of $1,000 to $60,000, you must hand the customer a written disclosure statement about bonds, insurance, and liens. Without it you cannot file a lien on that job

Checked by a person against the official page

·3 official pages

8 Does a plumber charge sales tax on labor in Washington? What is this?

In Washington, taxed. Same rule as above. The rest of the rules are below.

See how this compares in every state: Sales tax on labor for plumbers and HVAC contractors by state

Building for a customer	You charge retail sales tax on the whole contract price, labor and materials, and show it as a separate line on the invoice. This is called retail or custom construction and covers most jobs a plumber does for a homeowner or a business
Labor on homes (repairs and remodels)	Taxed. Same rule as above
Repairs and remodels on businesses	Taxed. Same rule as above
Labor on new buildings	Taxed when you work for the landowner or a prime contractor. Building on land you own to sell (speculative building) is taxed differently
Materials	You buy materials that become part of the building tax-free with a reseller permit. You pay sales tax on tools, supplies, and anything you use up on the job
Business and occupation tax	Your gross receipts from custom construction are also taxed under the Retailing B&O classification, a tax on the business itself that you do not pass to the customer
Tax rate	6.5 percent state rate plus the local rate for the job site

Checked by a person against the official page

·3 official pages

9 Getting paid: lien and notice deadlines for a Washington plumber What is this?

If you are not paid in Washington, a lien on the property is your backstop, but only if your notice goes out on time: send it early. The notice only protects work done in the 60 days before you send it, so anything older is lost (work started on March 1 and notice sent on June 1 covers only work from April 2 onward). On a new single-family house it covers only the 10 days before the notice.

Who has to send a notice	Subcontractors and suppliers who were not hired by the property owner send a Notice to Owner (the law calls it a notice of a right to claim a lien). If the owner hired you, you do not send this notice, but you must give the disclosure statement above on jobs of $1,000 or more. Workers claiming only for their labor do not send it either
Send your notice by	Send it early. The notice only protects work done in the 60 days before you send it, so anything older is lost (work started on March 1 and notice sent on June 1 covers only work from April 2 onward). On a new single-family house it covers only the 10 days before the notice
File your lien by	Record the lien with the county where the property sits within 90 days of your last day of work or last delivery (last work on June 1 means the lien is recorded by August 30)

Checked by a person against the official page

·3 official pages

10 How much does it cost to become a plumber in Washington? What is this?

The government fees on this page add up to about $706 in Washington. Add insurance, tools, and a vehicle to get the real number.

Government fees, added up	$706

Does not include the PSI scheduling fee, the $6,000 bond premium, insurance premiums, workers' comp, tools, a vehicle, or city permits. Add $150.20 if you also register as a general contractor

Our estimate

11Where these numbers come from

The labels under each table are explained on how to read a page.