Missouri Plumber Reciprocity

Missouri Has No Automatic Reciprocity

There is no statewide reciprocity agreement for plumbing licenses in Missouri. Because licensing is entirely local — controlled by individual cities and first-class counties — there is no state board to negotiate reciprocity with other states or even with neighboring Missouri jurisdictions. Each local board decides independently whether to recognize credentials from elsewhere.

This applies both to out-of-state plumbers moving to Missouri and to Missouri plumbers trying to work in a different city or county within the state.

How Out-of-State Transfers Work

If you hold a plumbing license from another state and want to work in Missouri, you apply directly to the local board where you plan to operate. The process is case-by-case:

Springfield is the most accommodating — the board accepts matching exam scores from Prometric, ICC, or Block testing services. If your out-of-state license was earned through an ICC exam with a passing score that meets Springfield's 75% threshold, you may be able to use that score instead of retesting.

St. Charles County accepts valid ICC test results without pre-authorization. If you passed an ICC master plumber exam in your home state, bring the score report to St. Charles County along with your contractor application.

Kansas City and Jefferson City evaluate applications individually. Expect to submit your out-of-state license details, exam records, and experience documentation for board review.

St. Louis County and St. Louis City are the hardest transfers. Both maintain proprietary exam systems (IAPMO for the County, city-administered for the City), and neither automatically accepts out-of-state credentials. You may need to sit for their local exam regardless of what you hold elsewhere.

Cross-Jurisdiction Within Missouri

The same fragmentation applies within the state. A Kansas City journeyman card does not authorize work in St. Louis County. A St. Charles County contractor license does not cover Jefferson County. Each expansion into a new jurisdiction means a new application, potentially a new exam, a new bond where required, and a new insurance certificate.

Some jurisdictions are more pragmatic about this than others. If you already hold a trade card from a reputable Missouri board and passed a recognized exam, certain boards may waive the exam requirement on review. But nothing is guaranteed — always confirm with the target board before bidding on out-of-area work.

HB 2394: The Proposed Fix

House Bill 2394, introduced in the 2026 legislative session by Representative Bill Falkner, proposes adding Section 341.240 to the Revised Statutes of Missouri. The bill would mandate that any political subdivision requiring a plumbing license must recognize a valid, active license from any other Missouri city or county — provided the licensee passed an approved trade examination.

Key provisions:

• Mandatory cross-jurisdiction recognition of valid local trade licenses
• Exam waiver for duplicate competency testing between jurisdictions
• Local business licenses and taxes still required — the bill waives exam duplication, not local registration and revenue collection

The bill received "Do Pass" recommendations from both the House Standing Committee on Local Government and the Standing Committee on Rules-Legislative. Proponents argue it would bring plumbing in line with the statewide reciprocity already established for Missouri electricians under Chapter 324.

Opponents, particularly local contractor associations, argue that regional code variations (St. Louis's combined sewer systems vs. newer suburban developments) justify jurisdiction-specific testing.

What to Do Now

Until HB 2394 becomes law (if it does), the practical approach is:

1. Get licensed in your primary jurisdiction first
2. Before expanding, contact the target board and ask specifically whether they accept your existing exam scores
3. If they require retesting, find out which exam vendor and code edition they use
4. Budget for separate bonds where required and insurance certificates in each jurisdiction

The Missouri Plumber License Guide includes a reciprocity comparison across seven jurisdictions and a cross-border expansion checklist for plumbers planning multi-county operations.

See more Missouri guides →