Plumbing Contractor License in Illinois: Requirements, Qualifier, Bond and Exams

Statewide.

Under the Illinois Plumbing License Law (225 ILCS 320), IDPH licenses plumbers, plumbing contractors, plumbers' apprentices, irrigation contractors and retired plumbers, and anyone performing plumbing for another person must register annually with IDPH as a plumbing contractor.

The plumbing itself must also be done by licensed plumbers or licensed apprentice plumbers, with homeowners doing their own single-family residence exempt.

IDPH's own plumbing page states that it licenses approximately 8,900 plumbers and 2,000 apprentice plumbers.

So the business registration and the individual licenses come from the same department; this page covers what the business needs, and individual plumber licensing is its own topic.

The Illinois Department of Public Health (IDPH) administers the plumbing contractor registration under the Illinois Plumbing License Law (225 ILCS 320).

There is no class system on record: our research shows a single plumbing contractor registration, with irrigation contractor registration the separate category beside it.

One structural wrinkle: a city of 500,000 or more may run its own board of plumbing examiners and issue plumber licenses under an ordinance containing provisions substantially the same as the state Act — in practice, Chicago.

Separately, Chicago adds its own contractor license layer (below).

On lookup: our research did not capture a public IDPH license-lookup URL for plumbing contractor registrations, so confirm a registration through IDPH's plumbing program page, and direct Chicago license questions to the city.

Illinois ties the registration to an individual license held inside the business: an Illinois plumbing contractor registration requires the plumbing license of the individual, if a sole proprietorship; the partner, if a partnership; or an officer, if a corporation.

The Act adds a staffing rule beside it — at least one member of every firm or partnership, and at least one corporate officer of every corporation, engaged in plumbing work must be a licensed plumber — and that person is the registration's qualifier in practical terms.

There is no journeyman or master tier in Illinois, so the qualifier holds the state's full plumber license.

That license itself takes at least 2 years of high school or equivalent and at least 4 years as an Illinois licensed apprentice plumber under supervision (or an approved plumbing course supervised by an Illinois licensed plumber), with the exam application filed at least 30 days before the exam.

HVACHires has a separate guide to naming a qualifier or qualifying agent for a contractor license.

Our research found no separate trade exam and no business-and-law exam attached to the IDPH plumbing contractor registration — confirm with IDPH before you plan around that.

The exam on record is for the plumber license itself: IDPH holds examinations for plumber license applicants at least once every three months, and an applicant must apply at least 30 days before the exam.

That cadence plus the experience route to a plumber license — at least 4 years as an Illinois licensed apprentice plumber, or the approved plumbing course alternative — is also your timeline for growing another licensed plumber inside the company.

The Act sets dollar minimums for the state registration: general liability of at least $100,000 per occurrence / $300,000 aggregate bodily injury and $50,000 property damage, or a $300,000 combined single limit, plus $500,000 in workers' compensation employer's liability, and a $20,000 indemnification bond — or a letter of credit in the same amount.

Keep the city layer separate in your head: Chicago's license carries its own $20,000 performance bond, filed with the City Clerk (below).

For how these instruments work in a contracting business, HVACHires' separate guide to contractor license bonds and insurance explains the mechanics.

The registration is annual, and the date is the same for every registered contractor in Illinois.

The IDPH registration fee was not captured in our research, so ask IDPH for the current fee before you budget.

Two more renewal dates belong on the business calendar: your qualifier's plumber license must be renewed by April 30 following issuance through IDPH's online renewal page, and each annual renewal after the first licence requires proof of 4 hours of continuing education.

That plumber license is the one your registration stands on, so a lapse there undermines the registration's foundation.

We did not find a reciprocity provision in the Illinois Plumbing License Law (225 ILCS 320), so we cannot tell you whether IDPH accepts another state's plumbing license, waives any requirement for out-of-state license holders, or credits out-of-state experience toward the 4-year licensed-apprentice minimum.

That is an absence in our research, not a confirmed no — Illinois may recognize out-of-state licenses in provisions we did not find.

If you hold a plumbing license from another state and want to qualify an Illinois registration, ask IDPH directly before you staff around it.

The registration requires the plumbing license of a specific person — the individual if a sole proprietorship, a partner if a partnership, or an officer if a corporation — and the Act separately requires at least one member of every firm or partnership, and one corporate officer of every corporation, engaged in plumbing work to be a licensed plumber.

If the person holding that license leaves, the license your registration rests on is gone until a licensed plumber takes the role.

What you must file with IDPH, and by when, our research does not establish: we found no replacement deadline and no notification rule for plumbing contractors, so ask IDPH for the substitution process before the departure, not after.

And growing a replacement is slow by design — at least 4 years as an Illinois licensed apprentice plumber (or an approved plumbing course supervised by an Illinois licensed plumber) before a candidate can sit the plumber exam — so keep the licensed plumbers who could step in employed, with licenses renewed by April 30.

Working in Chicago adds a city layer.

A plumbing contractor licensed by the State of Illinois must also obtain a City of Chicago plumbing contractor license to perform plumbing work within the City of Chicago: the applicant must be a Chicago-licensed plumber, and the business must file a $20,000 performance bond with the City Clerk.

The city license fee for calendar year 2026 is $150 initial and $150 renewal.

Continental Testing Services processes plumbing contractor license applications on behalf of the city's Department of Buildings and Board of Plumbing Examiners.

One staffing relief: employees of a Chicago-licensed plumbing contractor may be plumbers or apprentice plumbers licensed by either the City of Chicago or the State of Illinois.

Crew structure has its own licensing math.

An Illinois licensed apprentice plumber must be at least 16 and sponsored by an Illinois licensed plumber or an approved apprenticeship program, and an apprentice may not accumulate more than 6 years as an apprentice.

A licensed plumber may sponsor no more than 2 licensed apprentice plumbers at the same time, and if sponsoring 2, one must have at least 2 years as a licensed apprentice.

Since every employee doing plumbing must be a licensed plumber or a licensed apprentice plumber, hiring apprentices means counting sponsors first.