Washington Plumbing License Verification — How to Check a Plumber's Credentials

Whether you are a homeowner hiring a plumber, a contractor checking a new hire's credentials, or a plumber verifying your own status before an L&I audit, Washington makes license verification straightforward through a single public tool.

L&I's Verify a Contractor, Tradesperson, or Business Tool

The Department of Labor & Industries hosts a public search engine at lni.wa.gov under Licensing & Permits → Contractors → Verify a Contractor. It covers three types of records:

Individual certifications — enter the person's name or certification number to see their license type (PL01, PL02, PL04, MG01, etc.), issue date, expiration date, and current status (active, expired, suspended). The tool also shows any infractions or citations on record.

Contractor registrations — search by business name, UBI number, or contractor registration number to see the company's active bond amount, insurance status, and any L&I enforcement actions.

Trainee cards and hours — verify trainee renewal status and logged affidavits through L&I's certification portal rather than relying on the public contractor search.

What to Look For

A valid plumbing contractor should show three things simultaneously: an active contractor registration, an active surety bond, and current general liability insurance electronically verified through EBIPS. If any one of these is listed as expired or suspended, the contractor is not legally authorized to pull permits or perform plumbing work.

For individual plumbers, confirm that the certification type matches the work they are being hired to do. A PL02 holder cannot legally work on commercial projects. A PL04 holder is limited to residential service and repair — not new construction.

Why Verification Matters for Plumbers Themselves

The most common reason a plumber needs to verify their own record is before a license renewal or contractor registration filing. L&I's system updates asynchronously — an hour submission, CE credit, or bond renewal can take days to reflect. If you are submitting a renewal application and your record shows an incomplete CE requirement or a lapsed bond, L&I will reject the renewal and trigger the double-fee penalty clock.

Checking your own record before filing gives you time to follow up with your CE provider or bonding agent if their submissions have not posted.

For a full walkthrough of the verification system and what each status means for your certification path, the Washington Plumber License Guide includes the step-by-step verification process alongside the renewal and application checklists.

See more Washington guides →