How do you verify an HVAC or plumbing candidate's licence before hiring?
Which credentials to check for each role, where each one is verified, what to keep on file, and how to track renewals after the hire.
To verify a plumbing or HVAC candidate's licence before you hire, check each credential with whoever issued it: the state board's public lookup for a state licence, the city or county where licensing is local, and the certifying organization for EPA 608, NATE and ASSE cards.
A paper copy in a candidate's file is a claim, not proof — this page covers what to check, where to check it, and what to keep on file.
Which credentials should you check for each role?
The credentials to verify are set by the work, and the work differs by role and by state.
For a plumber, it is the state's journeyman- or master-level plumbing licence where the state issues one at the worker level.
For an HVAC technician, refrigerant work has a federal baseline: only EPA-certified technicians may buy refrigerant, with limited exceptions, and an employer may buy only by showing the wholesaler that it employs a certified technician.
What the state layer looks like varies more than a job title suggests.
Georgia licenses conditioned air contractors (Class I and Class II) and has no state licence for individual HVAC technicians; Michigan licenses mechanical work only at the Mechanical Contractor level and issues no journeyman or technician licence for HVAC workers.
So don't assume a generic "state HVAC licence" exists for your hire to hold — ask the state board which licence, if any, covers the technician level, pull the exact name from its materials, and write that name into the job ad so candidates can self-check before they apply.
Then add the role extras your jobs actually need: NATE certification (voluntary, and checked differently — below), a backflow prevention assembly tester qualification for cross-connection work, and medical-gas credentials where the shop takes hospital work.
Entry-level hires need the most care: before you schedule solo work for a hire who holds no card yet, ask your state board what an unlicensed helper may do under supervision, and how much oversight the helper needs — our apprentice supervision ratios guide covers the supervision side.
Where do you check a state or local licence?
Start from the board that issued the licence — the board keeps the public record.
Texas shows the pattern: TDLR's licence search covers ACR licences, for contractors and for technicians, and the Texas State Board of Plumbing Examiners links a "Find a License / Registration" look-up from its own site.
Verified official look-up tools exist for Alabama, Alaska, Arkansas, Connecticut, Florida, Georgia, Idaho, Louisiana, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon, Texas, Vermont, Washington and West Virginia.
In Arizona, California, Delaware, the District of Columbia, Kentucky, Michigan, Mississippi, Nevada, Oklahoma, South Carolina and Tennessee, our research saw a licence look-up linked from official pages but did not open or confirm the pages themselves — so reach the tool through the board's own website rather than a third-party "licence checker", and if a search returns nothing, call the board and ask it to confirm the licence status before you reject or hire on the strength of an empty result.
Where licensing is local, there is no statewide tool to check: Kansas, Missouri and Wyoming have no statewide HVAC or plumbing licence look-up, and there is none for HVAC in Illinois (Pennsylvania is likely the same, though that is unconfirmed).
Check the city instead — Kansas City, St. Louis County, Casper and Chicago are the examples our research noted.
The per-state tools for the plumbing side are gathered in our plumbing licence lookup guide.
How do you check EPA 608, NATE, backflow and med-gas cards?
EPA 608 runs through the certifying organization, not the agency: EPA does not issue 608 certification cards and cannot replace a lost card — the certifying organization issues and replaces them.
The organization named on the card is therefore the one to contact.
Two wrinkles help you judge older cards: cards issued by certifying programs that have since stopped testing remain valid if they were issued while the program was approved, and when the original certifying organization is out of business, EPA lists ESCO Institute and Ferris State University as organizations that will issue a replacement card to a technician with documentation of passing.
Certification itself does not expire under current rules.
NATE credentials do run on a clock: they must be renewed every two years, either by submitting 16 continuing education hours or by retaking the specialty exam before the period ends.
Ask when the technician last recertified, and check the dates on the certificate before you count it toward the hire — a credential on a two-year renewal cycle is only as current as its last renewal.
On the plumbing side, the ASSE Series 5000 professional-qualification standards include 5110 Backflow Prevention Assembly Tester, 5120 Cross-Connection Control Surveyor/Specialist, 5130 Backflow Prevention Assembly Repairer and 5150 Backflow Prevention Program Administrator.
Medical gas sits in ASSE Series 6000, whose 2024 edition parallels NFPA 99-2024 and covers 6005 generalist, 6010 installer, 6020 inspector, 6030 verifier and 6040 maintenance, among other roles.
ASSE certifications must be renewed every three years — and water utilities and states set their own backflow-tester renewal cycles, often annual or biennial, so for backflow testers the local rule governs.
What should you keep on file?
The credential itself: a copy of the licence or certificate showing its number, the issuing board or organization, and the expiry date where there is one.
This is the document you re-check at renewal and the one an inspector, a wholesaler or a GC may ask your company to produce.
The verification record: what the look-up or the issuer showed, and the date you checked it.
For EPA 608 that means the card copy plus the name of the certifying organization — EPA cannot replace a lost card, so the organization's record and the technician's documentation of passing are the proof that survives a move between shops.
The exact licence name as the board writes it, in both the job ad and the hire file.
A generic "must hold a state HVAC licence" line cannot be checked in a state that licenses the contractor business rather than each technician — Georgia and Michigan, from the first section, are the examples.
Write your state's own licence names into the posting template once, and every future ad and file inherits a requirement the board can actually match.
File all of it with the onboarding paperwork, so the renewal calendar below has a home from the first day.
How do you track renewals after hire?
Renewal cycles are set by each state's board, and they are not uniform.
Plumber licence renewal is annual in Alabama, Arkansas, Connecticut, Illinois, Kentucky, Louisiana, Montana, North Carolina, North Dakota, Oklahoma, South Dakota and Texas; every two years in Colorado, Delaware, the District of Columbia, Georgia, Indiana, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, Rhode Island, Vermont and Virginia; and every three years in Hawaii, Idaho, Iowa and Washington — with Michigan splitting the difference between journey (annual) and master (3-year).
Continuing education rides along: plumber CE ranges from none (Maryland, North Carolina, and Michigan outside code changes) to 4 hours a year (Alabama, Illinois, Montana) and up to 24 hours (Oregon; Washington per 3 years; Wisconsin).
On the HVAC side, some state licences carry no CE requirement — Maryland (HVACR), North Carolina, Michigan (mechanical contractor), Wisconsin (HVAC qualifier/registration) and Louisiana commercial (LSLBC) licences among them — and the highest HVAC contractor requirement in our research was Florida's 14 hours per 2 years.
The cards you checked at hire tick on their own clocks — NATE every two years, ASSE every three, and backflow testers on whatever cycle the water utility or state sets.
Put every expiry on the calendar on day one, re-run the board's look-up ahead of each renewal date rather than after it, and confirm with the board what a lapse means for the work that requires the licence.
With credentials verified and tracked, the rest of the process — sourcing, screening, pay, onboarding — is in our guide to hiring HVAC and plumbing techs.
This page is employer career and business information, not legal advice. Licensing and certification rules are set by state boards, cities, EPA and the certifying organizations — confirm current requirements and a licence's status with the issuer before you hire.
The verification file for each new hire
- A copy of the licence or certificate: number, issuing board or organization, and the expiry date where there is one.
- A dated record of what you checked — the board look-up (or the city's contractor list, where licensing is local) and what it showed.
- The EPA 608 card copy and the certifying organization that issued it — the organization, not EPA, holds the record and replaces lost cards.
- The state's exact licence name, written the way the board writes it, in the job ad and the hire file.
- Renewal dates on the calendar from day one: the state licence's, NATE (every 2 years), ASSE (every 3 years), and the water utility's backflow cycle where one applies.
Questions employers ask
How do I verify an EPA 608 certification?
EPA does not issue 608 certification cards and cannot replace them — the certifying organization named on the card issues and replaces them, so that organization is the one to contact.
If the certifying program has since stopped testing, cards issued while the program was approved remain valid.
If the original organization is out of business, EPA lists ESCO Institute and Ferris State University as organizations that will issue a replacement card to a technician with documentation of passing.
Does EPA 608 certification expire?
No — under current rules, EPA 608 certification does not expire.
The credentials that do run on renewal clocks are the voluntary and specialty ones: NATE certifications must be renewed every two years, ASSE certifications every three years, and state plumbing or mechanical licences on each board's own cycle.
If a card looks unusual, confirm its status with the organization that issued it.
How often do plumbing licences renew?
It depends on the state.
Plumber licence renewal is annual in Alabama, Arkansas, Connecticut, Illinois, Kentucky, Louisiana, Montana, North Carolina, North Dakota, Oklahoma, South Dakota and Texas; every two years in Colorado, Delaware, DC, Georgia, Indiana, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, Rhode Island, Vermont and Virginia; and every three years in Hawaii, Idaho, Iowa and Washington.
Michigan renews journey licences annually and master licences every 3 years.
What licence does an HVAC helper need?
Don't schedule solo work for an unlicensed helper until your state board tells you what a helper may do under supervision, and which card, if any, a helper must hold — that is a rule to look up with the board over your city or state, not something to infer from the job title.
Refrigerant handling is the federal baseline: only EPA-certified technicians may buy refrigerant, with limited exceptions, and an employer may buy only by showing the wholesaler that it employs a certified technician.
More hiring resources
The licence checks are set — now find the tech
Post your opening where HVAC and plumbing techs already look, next to the guides they read while they check their own credentials.