Plumbing Contractor Permit Requirements in Seattle, WA

1. EIN (Employer Identification Number)

   Required if you have employees or operate as an LLC/corporation. Free from the IRS.

   Official government source

   Free·Immediate (online application)

   Free

   Immediate (online application)

1. Washington State Contractor Registration

   All construction contractors in Washington must register with the Department of Labor & Industries. Registration requires a continuous contractor surety bond or assignment of savings, general liability insurance, workers' compensation coverage if you have employees, and a UBI number from the Department of Revenue. Specialty contractors may work only within their registered specialty and cannot hire subcontractors; general contractors can. A plumbing business must also hold a separate Licensed Plumbing Contractor license from L&I with a designated certified plumber.

   Official government source

   $150.20 registration fee (same amount to renew; $70.90 to reinstate a suspended registration), plus a continuous contractor surety bond or assignment of savings - $30,000 for general contractors, $15,000 for specialty contractors - and general liability insurance of $200,000 public liability / $50,000 property damage or a $250,000 combined single limit. Bond premiums vary by surety.·Applications mailed to L&I currently take 3-4 weeks to process and activate; applying in person at an L&I office is faster. The registration card arrives about 2 weeks after activation.

   $150.20 registration fee (same amount to renew; $70.90 to reinstate a suspended registration), plus a continuous contractor surety bond or assignment of savings - $30,000 for general contractors, $15,000 for specialty contractors - and general liability insurance of $200,000 public liability / $50,000 property damage or a $250,000 combined single limit. Bond premiums vary by surety.

   Applications mailed to L&I currently take 3-4 weeks to process and activate; applying in person at an L&I office is faster. The registration card arrives about 2 weeks after activation.

2. Washington State Plumber License

   Washington requires anyone doing plumbing work to hold a state plumber certification from the Department of Labor & Industries - Journey Level, Residential, Residential Service, or a specialty such as domestic pump or backflow assembly. There is no 'Master Plumber' level in Washington. A plumbing contracting business must additionally hold a Licensed Plumbing Contractor license with a designated certified plumber, and register as a contractor under RCW 18.27 with the required bond and liability insurance. Certification requires documented experience hours and passing a state competency examination.

   Official government source

   Plumber certification: $202.10 exam application to L&I (the testing contractor charges its own exam fee on top) plus $242.70 for the journey level, residential specialty, or residential service certificate, which covers 3 years. Licensed Plumbing Contractor: $148.10 for each 2-year issuance or renewal plus $53.20 for the initial identification of the designated plumber. Trainee certificate $60.00; temporary permit $100.30 for 120 days (WAC 296-400A-045). Separate L&I contractor registration is $150.20 plus a $15,000 specialty (or $30,000 general) surety bond.·L&I does not publish a guaranteed turnaround. Plan around exam scheduling with L&I's testing contractor plus processing of the certificate and the contractor license; mailed contractor registration applications currently take 3-4 weeks.

   Plumber certification: $202.10 exam application to L&I (the testing contractor charges its own exam fee on top) plus $242.70 for the journey level, residential specialty, or residential service certificate, which covers 3 years. Licensed Plumbing Contractor: $148.10 for each 2-year issuance or renewal plus $53.20 for the initial identification of the designated plumber. Trainee certificate $60.00; temporary permit $100.30 for 120 days (WAC 296-400A-045). Separate L&I contractor registration is $150.20 plus a $15,000 specialty (or $30,000 general) surety bond.

   L&I does not publish a guaranteed turnaround. Plan around exam scheduling with L&I's testing contractor plus processing of the certificate and the contractor license; mailed contractor registration applications currently take 3-4 weeks.

3. Washington Business Entity Registration

   LLCs and corporations must file with the Washington Secretary of State to form the entity, then register with the Department of Revenue through the Business License Application to get a Unified Business Identifier (UBI) and tax accounts. The two filings are separate.

   Official government source

   $180 Secretary of State original filing fee for an LLC or profit corporation (plus a small online processing fee), then a $70 annual report each year. $50 Business License Application processing fee with the Department of Revenue to open a new business/UBI, plus $5 per year to renew each location and any endorsement fees.·Secretary of State filings are worked in the order received with no published standard turnaround; expedited service is $100 per entity (generally three working days) and same-day service is $150. The state Business License takes about 10 business days online, plus 2-3 weeks more if city or state endorsements are needed.

   $180 Secretary of State original filing fee for an LLC or profit corporation (plus a small online processing fee), then a $70 annual report each year. $50 Business License Application processing fee with the Department of Revenue to open a new business/UBI, plus $5 per year to renew each location and any endorsement fees.

   Secretary of State filings are worked in the order received with no published standard turnaround; expedited service is $100 per entity (generally three working days) and same-day service is $150. The state Business License takes about 10 business days online, plus 2-3 weeks more if city or state endorsements are needed.

1. City of Seattle Business License Tax Certificate

   All businesses operating in Seattle must obtain a Business License Tax Certificate, administered by Seattle City Finance (License and Tax Administration). The certificate is required regardless of revenue; Seattle B&O tax is owed only if annual taxable gross revenue is $2 million or more (the threshold rose from $100,000 on January 1, 2026). Plumbing contractors must list their Washington State contractor registration number.

   Official government source

   $73/year if your Seattle taxable revenue is under $20,000, $147 for $20,000-$499,999.99, $667 for $500,000-$1,999,999.99, $1,604 for $2 million-$5 million, and $3,210 for more than $5 million (2026 fee schedule), plus $10 per branch location. Businesses that start July 1 or later pay half the first-year fee.·You can usually print the certificate within 2-3 business days after your payment processes.

   $73/year if your Seattle taxable revenue is under $20,000, $147 for $20,000-$499,999.99, $667 for $500,000-$1,999,999.99, $1,604 for $2 million-$5 million, and $3,210 for more than $5 million (2026 fee schedule), plus $10 per branch location. Businesses that start July 1 or later pay half the first-year fee.

   You can usually print the certificate within 2-3 business days after your payment processes.

2. Public Health - Seattle & King County — Plumbing Permit and Contractor Verification

   In Seattle, plumbing permits are issued and inspected by Public Health - Seattle & King County, which enforces the Seattle Plumbing Code (not SDCI). Plumbers must hold a Washington State L&I plumber certificate and the contractor must hold L&I contractor registration; a City of Seattle business license is also required. There is no separate city plumbing exam.

   Official government source

   No additional fee·1–3 days

   No additional fee

   1–3 days

Official Sources

• Washington State Department of Labor and Industries — Plumbing
• Washington State Department of Labor and Industries — Contractor Registration
• City of Seattle — Business License

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