What an LMP actually is
A Licensed Master Plumber is a license issued by the NYC Department of Buildings to a person, not a company. Earning one takes years of documented experience in the trade plus examinations — it is closer to a professional credential than a business registration. The LMP is legally responsible for every job performed and filed under their license, which is why the number follows the person, appears on permits, and is painted on the side of the truck.
Plumbing businesses operate under an LMP of record. The crew at your door may be journeymen and apprentices — that's normal and fine — but the work is performed under a specific master plumber's supervision and license. When you verify, you're verifying that person and that number, not just a brand name and a logo.
Why the license matters more in NYC than almost anywhere
Two words: gas and permits. In NYC, gas piping work — connecting a stove, moving a gas line, replacing a gas water heater — may only be performed by a Licensed Master Plumber or someone working under one. The failure mode for bad gas work isn't a drip; it's carbon monoxide or an explosion. The city's licensing regime exists because both have happened here.
Permits are the second lever. Only an LMP can file plumbing and gas permits with the Department of Buildings — homeowners cannot self-file plumbing work the way some jurisdictions allow. Unpermitted work doesn't stay invisible: it surfaces at sale, at refinance, in co-op alteration reviews, and in insurance claims, where a denial over unlicensed work costs far more than the permit ever would.
There's also a plain accountability point. A license is something a plumber can lose. That gives the DOB roster teeth: an LMP who does dangerous or fraudulent work has something real at stake beyond one bad review. An unlicensed operator has nothing at stake except your deposit.
How to look up the license
Ask for two things before anyone starts work: the license number and the name it's issued to. A legitimate shop gives both without friction — the number is already on the truck and the paperwork. If getting the number feels like pulling teeth, you've learned what you needed to know.
Then check it. The Department of Buildings runs a public online license search — reachable through the DOB's website and searchable by name or license number — showing whether a license is active, when it expires, and who holds it. The same roster is published on the city's NYC Open Data platform if you prefer a dataset to a search box. Confirm three things: the status is active, the expiration date hasn't passed, and the name matches the person — or the LMP of record for the company — on your contract.
For larger jobs, go one step further: ask which LMP will file the permit, and match that name to your contract. Licensed plumbers also carry DOB-issued license identification, and asking to see it is normal in this city, not rude.
Insurance: ask for the COI
A license proves the right to do the work; insurance pays when something goes wrong anyway. Ask for a certificate of insurance (COI) showing general liability and workers' compensation, with coverage dates that span your job. Any established shop produces this routinely — buildings and managing agents demand it for almost any alteration, so the broker can email it the same day.
For substantial work, ask to be named as certificate holder, and have the certificate sent directly from the insurance broker rather than handed over as a photocopy. A COI direct from the broker is current by definition; a PDF from a folder might be last year's. If you live in a co-op or condo, your managing agent will likely require exactly this anyway — the building's COI requirements are a free filter for who's legitimate.
Red flags that mean walk away
Cash only, no paperwork. No license number on the truck, the estimate, or the contract — licensed shops display the number because the law expects it and because they earned it. A price strangely far below everyone else's usually has the license, the insurance, or the permit missing from the math.
“You don't need a permit for this” — said about gas work, new piping, or relocating fixtures — is the loudest red flag in the trade. Some like-for-like repairs genuinely are exempt, but a professional tells you which side of the line your job falls on and files when filing is required. Related: anyone who suggests you pull the permit yourself is asking you to do something NYC doesn't allow for plumbing work, which tells you how they operate.
Watch for prices that move after work starts without a written change order, pressure to skip the COI “to save time,” and reluctance to put the LMP's name on the contract. None of these is a quirk. The corners someone cuts before the job are the corners they'll cut during it.
What Reset verifies before a profile goes live
Every plumber on Reset is verified against the NYC DOB license roster before their profile appears — license active, name matched to the business, number displayed on the profile. When Reset's own crew takes a job, it is labeled In-House, never disguised as an independent shop. Reviews on profiles come only from jobs booked through Reset, so nobody can paper over a record with imported stars.
Reset is a young network — we're recruiting the Founding 50 now — and we'd rather show you a short, honestly verified roster than a long padded one. Verification is the floor, not a favor. And because the DOB roster is public record, you can re-check anything we show you yourself, anytime. We think that's how it should work.