What is workers' compensation class code 5183?

Class code 5183 is the California workers' compensation classification for plumbing work, and it is one half of a dual-wage pair with code 5187. The Workers' Compensation Insurance Rating Bureau of California (WCIRB) assigns each plumbing employee's payroll to one code or the other based on the employee's regular hourly wage measured against a threshold WCIRB sets. Payroll for plumbers paid below the threshold goes to 5183; payroll for plumbers paid at or above it goes to 5187, which carries a lower rate per $100 of payroll.

The threshold is $35 per hour for policies effective on or after September 1, 2026 (approved by the Insurance Commissioner on May 15, 2026). It was $32 for policies effective September 1, 2024 through August 31, 2026, and WCIRB adjusts it periodically, so use the figure for your policy's effective date.

Two things matter in practice:

• The split is documented or it does not exist. The regular hourly wage and hours worked must be verifiable from payroll and time records. Payroll you cannot document is assigned to 5183, the higher-rated code, at audit.
• Not everyone on your payroll belongs in 5183 or 5187. Office staff whose duties fit code 8810 (clerical) and estimators or salespeople who fit 8742 (outside sales) can be rated separately, at much lower rates, if their duties and your records support it. Someone who answers phones in the morning and runs calls in the afternoon is plumbing payroll.