Which code in the 5183/5187 pair is the cheaper one?

5187 is the high-wage code and it is the cheaper of the two. In WCIRB pair notation the first code listed is always the low-wage code and the second is the high-wage code, and the high-wage code carries the lower rate because the plan assumes better-paid crews are more experienced.

What happens if a plumbing contractor reports everything to one code?

The auditor reallocates the work to the correct sub-classification and then tests each employee against that sub-classification's own threshold. That is two corrections in one audit, applied retroactively across the policy period. Because payroll not shown to meet a threshold defaults to the low-wage code, incomplete records make the outcome worse rather than neutral.

California Plumbing and HVAC Class Codes 5183 vs 5187 — Three Sub-Classes, Two Thresholds

Q: What is the California plumbing dual-wage threshold for 2026?

For policies incepting on or after September 1, 2026, the plumbing threshold rises from $32.00 to $35.00 per hour. Payroll for a plumber whose regular hourly wage equals or exceeds $35.00 is assigned to class code 5187(1); below that, it goes to 5183(1). The same $32 to $35 move applies to the refrigeration equipment and heating or air conditioning equipment sub-classifications.

Q: Is HVAC the same class code as plumbing in California?

Partly. Heating or air conditioning equipment installation is a sub-classification of the same pair, 5183(3)/5187(3), with the same $35.00 threshold from September 1, 2026. But heating or air conditioning ductwork is a different classification entirely: 5538(2)/5542(2), whose threshold rises from $33.00 to $37.00. A contractor doing both equipment and ductwork is in two different pairs with two different thresholds.

Evan Swan

Aug 19

5 min read

Updated: Sep 7

Quick answer

California plumbing is a dual-wage pair written 5183/5187 — 5183 is the low-wage code, 5187 the high-wage and cheaper one. The threshold rises from $32.00 to $35.00 for policies incepting on or after September 1, 2026. The pair carries three sub-classifications: plumbing 5183(1)/5187(1), refrigeration equipment 5183(2)/5187(2), and heating or air conditioning equipment 5183(3)/5187(3) — all at $35.00. Ductwork is elsewhere: 5538(2)/5542(2), rising from $33.00 to $37.00.

Source: WCIRB September 1, 2026 Regulatory Filing Quick Reference Guide and WCIRB classification search.

Will we write it? Tell us the operation, the state, and roughly where the mod sits — we'll come back within one business day with a straight answer: yes, no, or what we'd need to see. No ACORD, no loss runs, no obligation. Agents and business owners both welcome. Run it past us here.

The sub-classification is what appears on the policy

Most published dual-wage tables show sixteen rows and put "plumbing" on one of them. The WCIRB filing is finer than that. The 5183/5187 pair breaks into three sub-classifications with their own phraseology, and the sub-class — not the trade name — is what gets written on the policy and tested at audit:

5183(1) / 5187(1) — Plumbing. Threshold $32 → $35.
5183(2) / 5187(2) — Refrigeration equipment. Threshold $32 → $35.
5183(3) / 5187(3) — Heating or air conditioning equipment. Threshold $32 → $35.
5538(2) / 5542(2) — Heating or air conditioning ductwork. A different pair entirely. Threshold $33 → $37.
5185 / 5186 — Automatic sprinkler installation. Also separate. Threshold $33 → $36.

A mechanical contractor that installs rooftop units and fabricates the ductwork is operating in two different pairs at two different thresholds — $35.00 for the equipment work and $37.00 for the ductwork. The same technician can be high-wage on one and low-wage on the other in the same week. Reporting all of it to one code is one of the most common expensive audit findings in California mechanical work.

Why the low thresholds make this trade unusually exposed

At $35.00, plumbing has one of the lower thresholds in the table — well under carpentry and steel framing at $46.00 or the earthwork classes at $45.00. That sounds like good news and often is not, because it puts the cliff right in the middle of the wage band where residential service plumbers and second-year HVAC techs actually sit. A trade whose threshold is above the entire crew's pay scale produces a predictable, budgeted result. A trade whose threshold sits inside the pay scale produces a payroll split that has to be reported correctly every period, and a wage report that gets audited.

The $3.00 move from $32.00 to $35.00 pulls every plumber and tech earning between those figures out of the cheaper code and into the more expensive one, with no change in the work, the crew, or the risk.

Three mechanics that decide the outcome

It is a cliff, not a slope. A plumber at $34.99 is entirely low-wage payroll; at $35.00, entirely high-wage. Nothing blends or prorates.
It applies employee by employee. Not to the crew, not to a company average, not to a shop rate.
"Regular hourly wage" is a defined term. Overtime premium, bonuses, and per diem generally do not count toward it — which matters more in plumbing than most trades, because service work runs heavy on call-out premiums and commission-style spiffs that owners casually fold into "what he makes an hour."

Raise or reclassify? Run it per employee

List every employee earning between $32.00 and $34.99 — and separately, every ductwork employee between $33.00 and $36.99. Those are the ones that move.
Cost of the raise = (new threshold − current wage) × annual hours, plus payroll tax and benefit load.
Cost of reclassification = annual payroll ÷ 100 × the rate difference between the two codes × the experience mod.
Compare. Remember the mod multiplies the reclassification cost but not the wage cost — so the worse the mod, the more often the raise wins.

We run this side by side across ten verified trades in our break-even-by-trade guide, and keep every threshold current in the dual-wage tracker.

What else lands on the same renewal

September 1, 2026 also brings a 10.4% advisory pure premium increase and a set of Experience Rating Plan amendments. On top of the carrier rate, California layers statutory assessments we break down in our DIR surcharges guide. Price the all-in cost, not the manual premium.

The burden of proof sits with the employer

Assignment to a high-wage classification is subject to verification at final audit, and payroll not shown to meet the threshold is assigned to the low-wage code by default. For a mechanical contractor that split work across equipment, ductwork, and sprinkler classes, the records have to prove both the classification and the wage — job costing that ties hours to the right sub-class, and a wage calculation that matches the plan's definition. Our audit disputes handbook covers the dispute path when it comes back wrong.

Plumbing and HVAC dual-wage FAQ

What is the California plumbing dual-wage threshold for 2026?

It rises from $32.00 to $35.00 for policies incepting on or after September 1, 2026. At or above $35.00 the payroll goes to 5187(1); below it, to 5183(1). Refrigeration equipment and heating/air conditioning equipment move to the same $35.00 figure.

Is HVAC the same class code as plumbing in California?

Partly. HVAC equipment installation is a sub-class of the same pair — 5183(3)/5187(3), $35.00 threshold. But ductwork is a different classification: 5538(2)/5542(2), threshold rising from $33.00 to $37.00. A contractor doing both is in two pairs at two thresholds.

Which code in the pair is the cheaper one?

5187 — the high-wage code. In WCIRB pair notation the first code listed is always the low-wage one, and the high-wage code carries the lower rate.

What happens if a contractor reports everything to one code?

The auditor reallocates the work to the correct sub-classification and then tests each employee against that sub-class's own threshold — two corrections in one audit, applied retroactively. And because payroll not shown to meet a threshold defaults to the low-wage code, incomplete records make it worse rather than neutral.

Placing a California mechanical contractor

CPR Business Solutions is a wholesale workers' comp MGA placing hard California construction risk since 2021. Send the ACORD 130, five years of loss runs, the mod worksheet, and a wage report split by sub-classification, and we'll tell you what markets we can bring — or submit the account.

Call 714-928-3858 or email proposals@cprbrokers.com to talk through a California account.