The floor is 16: under U.S. Department of Labor rules, a registered apprentice must be at least 16 unless another law sets a higher minimum age.
At the other end, federal rules set no maximum age, and registered programs may not discriminate against apprentices and applicants aged 40 or older — though a program's standards and state law can add rules of their own.
Here is how both ends work, plus what you can do before 18.
Minimum age: 16 for registered apprenticeship programs
The federal floor comes from the U.S. Department of Labor's registered-apprenticeship rules: under 29 CFR 29.2, a registered apprentice must be at least 16 years old, except where a higher minimum age standard is otherwise fixed by law.
If you are 16 and meet the program's other entry standards, you are old enough for a registered HVAC or plumbing apprenticeship under federal rules.
Read the "except where" closely, because both halves of it matter.
Where another law fixes a higher minimum age, that higher age governs.
And the 16-year figure is a floor, not an entitlement: individual program sponsors may set other qualifications of their own, so the standards of the program you apply to sit on top of the federal floor.
The answer to how old you have to be to be an apprentice is therefore two layers — 16 under the federal rule, plus whatever entry standards your specific program adds on top.
One practical note for 16-year-olds: turning 16 opens the door, but being under 18 still matters once you are on the job, because the federal child-labor Hazardous Orders restrict certain work at 16 and 17.
That is the next question.
Youth apprenticeships: what you can do under 18
At 16 and 17, federal child-labor rules still apply: the Department of Labor's Hazardous Orders (29 CFR part 570) bar work in occupations declared particularly hazardous at those ages.
So the under-18 question is not only whether you can be admitted — it is what you can do once you are on site.
Registered apprentices get a partial answer.
A 16- or 17-year-old registered apprentice may do some work the Hazardous Orders would otherwise bar, but only when all of these hold:
- The work is incidental to the apprentice's training.
- It is intermittent and for short periods of time.
- It is under the direct and close supervision of a journeyman.
- The apprentice is registered in the program.
Treat that list as narrow, because it is: only some sections of the Hazardous Orders contain this apprentice exemption, so work covered by the other sections stays off-limits at 16 and 17.
What a specific program will actually assign a 16- or 17-year-old is a question for that program's sponsor.
If you are mapping this route from school, our guide to going from high school to HVAC covers the school-side options — CTE and vocational programs, dual enrollment and youth apprenticeships among them.
Confirm the under-18 rules before a minor starts specific work
Is there a maximum age to start an apprenticeship?
No. Federal registered-apprenticeship rules set no maximum age, and 29 CFR part 30 prohibits discrimination against apprentices and applicants aged 40 or older in registered programs.
The anti-discrimination layer underneath is broader than registered programs alone.
EEOC regulations state that all apprenticeship programs, including those created or maintained by joint labor-management organizations, are subject to the Age Discrimination in Employment Act, and that age limits in apprenticeship programs are valid only if they fit an ADEA exception or an EEOC exemption.
In practice, a hard age ceiling in an apprenticeship program is generally invalid unless it fits one of those exceptions.
Two caveats keep that answer honest.
First, "no maximum age" describes the federal rules' silence — the absence of a ceiling in 29 CFR parts 29 and 30 — not a promise about any individual admission decision.
Second, individual sponsors may set other qualifications of their own, and state law may differ, so the document that actually governs your application is the sponsor's written standards.
If age is your worry, read those standards and ask the sponsor directly.
Starting later also changes the picture in ways the age rules don't.
Our guides to a career change to HVAC and to becoming a plumber later in life cover the career-change side of each trade.
Age and union apprenticeship programs
The United Association describes its apprenticeships as registered with the Department of Labor, typically five years long, and covering plumbing, pipefitting, HVACR and related work.
Registered is the word that matters for age: the same federal rules attach to every registered program — the 16-year minimum, and part 30's protections for apprentices and applicants aged 40 or older.
The ADEA reaches union-side programs directly.
EEOC regulations apply the Act to all apprenticeship programs and name joint labor-management programs explicitly — so a union-side apprenticeship sits inside the same anti-discrimination rule as any other program, not outside it.
Beyond the federal floor, the sponsor's own standards control.
Federal rules contemplate that individual sponsors — union JATCs among them — may set other qualifications, so an age question at a specific program is answered by that program's written standards, not by a national rule.
Ask the sponsor, ideally in writing, before you build an application plan around an assumption.
Our guide to the union plumbing apprenticeship covers how JATC programs take applications and what they screen for.
Career information, not legal advice. The age rules on this page come from federal registered-apprenticeship and child-labor regulations; program sponsors and states add requirements of their own. Confirm the rules that apply to your situation with your program sponsor, and with the U.S. Department of Labor or your state apprenticeship agency where they govern.