Why the license matters
In New York City, plumbing is a licensed trade. The Department of Buildings (DOB) issues Licensed Master Plumber (LMP) licenses, and permits for plumbing work are only issued to a Licensed Master Plumber. Only LMPs, or the employees they supervise, may work on piping systems (DOB plumbing requirements). A handyman without a license can't legally pull a plumbing permit, and unpermitted work can cause violations and insurance problems for owners.
Step 1: Get the license number
Ask for it. DOB rules require a master plumber to put their license number and business information on their trucks and business cards. A real LMP will give it to you without hesitation. On this site, every listing shows the number.
Step 2: Look it up on DOB's License Search
Go to the DOB License Search. Choose Master Plumber and search by last name, business name, or license number. Confirm three things:
- The license status says Active.
- The name and business match the person and company you're hiring.
- The insurance on file is current.
Step 3: Check the disciplinary record
DOB publishes discipline for licensed plumbers: fines, probation, suspensions, revocations and voluntary surrenders. Search the Know Your Construction Professional directory and scan DOB's Licensed Plumbers disciplinary list.
Step 4: Make sure the permit is filed in their name
For work that needs a permit, the permit should be filed by the licensed master plumber you hired. Ask for the job or permit number and look up your building in DOB's systems. Our listings show how many Bronx permits each plumber pulled in the last 12 months, which tells you they actively file work here.
For landlords and property managers: gas piping inspections
Under Local Law 152 of 2016, gas piping in every building except one- and two-family homes and other R-3 buildings must be inspected by a Licensed Master Plumber at least once every four years, on a schedule set by community district. The LMP must give you a report within 30 days, and you file the certification with DOB within 60 days. Missing the filing can mean a $5,000 civil penalty. Details: DOB gas piping inspections.
Red flags
- No license number, or a number that belongs to someone else.
- "We don't need a permit for that" on gas, boiler, or new piping work.
- Cash only with no written estimate.
- A license that shows Expired, Suspended, or Revoked.
FAQ
Who can do plumbing work in NYC?
Only a Licensed Master Plumber (LMP), or employees the LMP supervises, may work on piping systems, and DOB issues plumbing permits only to LMPs (or Licensed Master Fire Suppression Contractors for fire suppression work).
How do I check a plumber's license in NYC?
Use the NYC Department of Buildings License Search. You can search by name, business name, or license number, and the result shows whether the license is active.
Where can I see if a plumber was disciplined?
DOB's Know Your Construction Professional directory and its Licensed Plumbers disciplinary list show fines, suspensions, probation, revocations and surrenders.
Does my building need a licensed plumber for gas piping inspections?
Yes, for most buildings. Under Local Law 152 of 2016, gas piping in all buildings except one- and two-family homes and other R-3 buildings must be inspected at least every four years by a Licensed Master Plumber or a qualified person working for one.
Sources: NYC Department of Buildings pages linked above, checked October 2026. Not legal advice.