Washington Plumbing Workers Comp Rates (2026)
Washington employers buy plumbing workers comp from the state fund. The 2026 rate for class 0306 (Plumbing, N.O.C.) is $1.82 per hour worked, before your experience factor.
Washington charges for every hour worked, not per $100 of payroll. Source.
Washington class code for plumbing
- 0306: Plumbing, N.O.C.
Monopolistic state fund (no private carriers) with its own four-digit risk classes and subclasses in WAC 296-17A that do not match NCCI codes, and premiums are charged per hour worked rather than per $100 of payroll, with workers paying part of the premium through payroll deduction.
Plumbing work involves back strain, cuts, burns from soldering and hot water, and work in crawl spaces and other confined spaces.
What comp costs per plumber in Washington
The Bureau of Labor Statistics counts 12,470 plumbers, pipefitters, and steamfitters on payrolls in Washington (May 2025), the 12th largest workforce among the 50 states and DC. The median wage is $38.96 an hour, 27% above the US median of $30.67.
Plumbers, pipefitters, and steamfitters make up about the same share of Washington jobs as they do nationally (location quotient 1.17).
Washington charges by the hour, not by payroll. The 2026 state fund rate for class 0306 is $1.82 for every hour worked, so a full-time worker costs about $3,790 a year and a 2-person crew roughly $7,580, before your experience factor. You pay $1.51 of each hour; the rest can be deducted from the worker's pay.
Because premium follows hours rather than wages, a senior hand at the 90th percentile costs the same to insure as a new hire. That is roughly $4.68 per $100 of payroll at the median Washington wage, the figure used in the comparison below.
Workers comp requirements in Washington
- Coverage required: Any employee (no minimum headcount)
- Owners and sole proprietors: Owners and exempt officers may buy elective coverage; employees must always be covered
- State fund: Monopolistic; coverage only from the state Department of Labor & Industries (L&I), or qualified self-insurance
- Waiting period: 3 days; paid only if the worker is still off on the 7th day
- Penalty for going without: Up to twice the premiums owed or $1,000, plus up to 100% of claim cost if unregistered
Washington uniquely calculates premiums by hours worked rather than payroll, and lets employers withhold part of the premium from employee wages.
Washington vs neighboring states
Washington has the highest plumbing comp rate in its region; every neighboring state charges less per $100 of payroll.
If your crews cross into Idaho or Oregon, your Washington state-fund coverage does not follow them. Buy a private policy for the out-of-state work, with Washington excluded from it.
What moves a plumbing comp bill
- Plumbing rates sit in the middle of the construction classes; the swing comes from your experience mod. Trench and excavation injuries are the costly claims, so trench-safety training pays back quickly.
- Some states split residential and commercial plumbing into different classes. If you do both, make sure the payroll for each is recorded so the cheaper work is not rated at the higher class.
- Apprentices carry the same class rate as journeymen, but their lower wages mean less premium per hour. Your payroll mix matters as much as the rate.
- Uninsured subs (excavators, drywall patchers) get added to your payroll at audit unless you collect certificates before they start.