Contractor registration covers a business. It says the company is bonded, insured and entitled to offer contracting services. What it does not tell you is anything about the person who actually turns up.
For plumbing and electrical work, Washington closes that gap. Both trades operate under individual certification requirements, which means the person doing the work holds credentials of their own that you can verify separately.
Why it exists for these two trades
Plumbing and electrical work fail in ways that are hidden, delayed and dangerous. A badly installed circuit does not announce itself; it sits in a wall until it becomes a fire. A poorly made plumbing connection can weep inside a cavity for years before anything appears downstairs.
Because the consequences are severe and the defects invisible, both trades carry individual competence requirements alongside the business-level registration, along with a system of trainees working under supervision.
What to ask
The question is simple and entirely normal: is the person doing the work certified, and can I see it? Any legitimate tradesperson expects this occasionally and will not be offended.
On larger jobs it is reasonable for trainees to be on site, working under supervision — that is how the trade reproduces itself and it is not a problem. What matters is that the supervision is real and that certified personnel are responsible for the work.
The permit connection
Most electrical work in Washington requires a permit and an inspection, and plumbing work often does depending on scope. This is a second layer of protection and one worth valuing rather than resenting.
An inspection means an independent party looks at the work before it disappears behind drywall. A contractor suggesting you skip a permit that is genuinely required is proposing to remove that check, and the saving is trivial compared with what it costs you.
Both layers, not one
Check both. The business should hold active L&I registration with a current bond and insurance. The individual should hold current certification for the trade.
A certified electrician working for an unregistered business leaves you without a bond. A registered business sending uncertified personnel leaves you without competence assurance. The two checks answer different questions and you want both answered.
Why this is worth the effort
Electrical and plumbing defects are the ones you discover late. Roofing problems announce themselves with water. Cabinetry problems are visible from across the room. A poorly made electrical connection is silent until it is not, and by then the work is buried.
Verifying competence beforehand is the only practical check available, because inspecting the result yourself is not an option.