A workers comp class code is a four-digit number assigned by NCCI (or a state rating bureau) that groups employees by the type of work they perform. Insurers use the class code to set a base rate — the cost per $100 of payroll — so a roofer carries a different rate than an office clerk. Who this is for: Business owners, HR managers, or brokers trying to understand how their premium is calculated and whether their employees are coded correctly.
TL;DR — Key Takeaways
- Class codes drive your premium. Every employee is assigned a code; the wrong code can inflate your bill by hundreds or even thousands of dollars per year.
- NCCI publishes the codes nationally, but eleven states (CA, DE, IN, MA, MI, MN, NJ, NY, NC, PA, WI — verify state) maintain their own independent rating bureaus with their own code sets.
- Payroll is the audit basis. At policy expiration, your carrier audits actual payroll and adjusts your premium based on what was really paid per class code.
- Experience modification factor (EMR) multiplies the class-code rate. A clean safety record (EMR < 1.0) reduces premium; a history of claims raises it.
- Misclassification is common and costly — either overpaying due to a too-hazardous code, or triggering audit penalties for an under-hazardous one.
What Is a Workers Comp Class Code?
A workers comp class code (sometimes called a "classification code" or "rate code") is a standardized four-digit identifier that describes the dominant work activity of a group of employees. The National Council on Compensation Insurance (NCCI) maintains the most widely used classification system, which covers 37+ states. Remaining states use independent bureaus that publish their own analogous code sets.
Each code is associated with a loss cost or manual rate — a dollar figure expressed per $100 of payroll. That rate reflects the historical injury frequency and severity for workers performing that category of work. Carriers then apply their own multiplier (called a loss cost multiplier or LCM) on top of the NCCI loss cost to arrive at the rate they charge.
Example rates by trade (illustrative ranges — not a guarantee):
| Class Code (NCCI) | Description | Typical Base Rate per $100 Payroll |
|---|---|---|
| 5183 | Plumbing — residential/commercial | $4.00–$7.50 |
| 5551 | Roofing — all kinds | $15.00–$30.00 |
| 8810 | Clerical office employees | $0.15–$0.40 |
| 5645 | Carpentry — residential construction | $9.00–$16.00 |
| 7229 | Trucking — long haul | $7.00–$12.00 |
| 8742 | Outside sales/business development | $0.25–$0.65 |
| 5022 | Masonry — commercial | $5.50–$9.00 |
| 9014 | Janitorial services | $2.00–$4.50 |
Rates vary significantly by state, carrier, and individual account history. Always request a formal quote for your specific operations.
How Class Codes Are Assigned to Your Business
Correct assignment follows a defined process:
- Describe your operations in detail. Your broker or carrier underwriter collects information on every type of work your employees perform — job titles alone are not sufficient.
- Identify the governing classification. If an employee performs multiple duties, the code covering the highest-hazard activity generally governs (with exceptions for clearly separate and distinct operations).
- Check state-specific rules. If you operate in a state with an independent bureau (California, New York, etc.), codes and rates are published by that state's bureau, not NCCI.
- Review the NCCI Scopes manual entry. Each code has a formal written description ("Scopes of Basic Manual Classifications") that defines exactly what it covers and what it excludes.
- Document payroll by class code. Your payroll system must track wages separately for each code so the audit has accurate data.
- Confirm at policy inception and at renewal. Codes can change when your operations change — adding a new service line may introduce a new code.
How Class Codes Affect Your Workers Comp Premium
The premium formula is straightforward once you understand the inputs:
Estimated Premium = (Payroll ÷ 100) × Class Code Rate × Experience Mod (EMR)
| Factor | What It Is | Who Controls It |
|---|---|---|
| Payroll | Actual wages paid per code | You (audit verified) |
| Class code rate | NCCI/bureau base loss cost × carrier LCM | NCCI/bureau + carrier |
| Experience mod (EMR) | 3-year loss history vs. expected losses | Your safety record |
| Schedule credit/debit | Carrier underwriting adjustments | Carrier discretion |
| State surcharges | Mandatory state assessments | State |
An EMR of 0.85 means you pay 15% less than the manual rate. An EMR of 1.30 means you pay 30% more. For a business with $1M in payroll across a code rated at $5.00/$100, that difference is $22,500 per year in premium alone.
Common Misclassification Scenarios
Misclassification is the single most common cause of incorrect workers comp premiums. It runs in both directions:
Over-classification (paying too much): A general contractor's in-house estimators are coded as 5606 (contractor — project manager/supervisor) instead of 8742 (outside sales), adding several dollars per $100 of payroll unnecessarily.
Under-classification (audit liability): A landscaping company codes maintenance workers as 0042 (landscape gardening — no tree work) when they regularly trim trees above 15 feet, which falls under 0106 (tree pruning/trimming/removal) at a significantly higher rate. At audit, the carrier reassigns payroll to the correct code and issues a large additional premium bill.
Real-World Example: Electrical Contractor in Texas
This is an illustrative scenario, not a guarantee of any specific premium.
Situation: Lone Star Electric LLC, a Houston-based commercial electrical contractor, has 12 employees and $960,000 in annual payroll: - 10 field electricians: $840,000 payroll → NCCI code 5190 (electrical wiring — commercial) @ $4.75/$100 - 2 office/admin staff: $120,000 payroll → NCCI code 8810 (clerical) @ $0.22/$100
Estimated manual premium: - Field: ($840,000 ÷ 100) × $4.75 = $39,900 - Office: ($120,000 ÷ 100) × $0.22 = $264 - Manual premium: $40,164
With an EMR of 0.90 (clean record, minor claims): $40,164 × 0.90 = $36,148
If the carrier had incorrectly coded all employees under 5190 (missing the clerical split), the admin payroll would carry the higher electrician rate, inflating premium by roughly $4,900/year. Over three years, that's about $14,700 in unnecessary cost — easily corrected by a class code audit from an independent agent.
FAQ — Workers Comp Class Codes
What is a workers comp class code, exactly? A workers comp class code is a four-digit number assigned by NCCI or a state rating bureau that groups employees by job type and determines the base rate (cost per $100 of payroll) used to calculate your premium. Each code reflects the historical injury risk for that category of work.
Who assigns my class codes — the government or my insurer? The codes are developed and maintained by NCCI (nationally) or an independent state bureau. Your insurer applies those codes to your workforce, but an independent broker can review the assignments and challenge errors on your behalf.
Can I use one class code for all my employees? Only if all employees perform the same type of work. NCCI rules generally require separate codes for clearly distinct operations and mandate that payroll be split and tracked accordingly.
What happens if my class codes are wrong at audit? If employees were under-classified (lower-risk code than actual work), you'll owe additional premium at audit. If over-classified, you may receive a return premium. Either way, the carrier will correct the codes going forward.
Do class codes differ by state? Yes. NCCI codes apply in 37+ states, but California, New York, New Jersey, Massachusetts, Pennsylvania, and several others use independent bureau codes that may differ in both number and rate. Always confirm which bureau governs your state.
How does the experience mod (EMR) interact with my class code rate? The class code rate sets your "manual" baseline. The EMR — based on your 3-year claims history compared to expected losses for your codes — multiplies that baseline up or down. A 1.25 EMR on a $50,000 manual premium means you pay $62,500; a 0.80 EMR means $40,000.
Can I negotiate my class code? You cannot negotiate the published rates, but you can — and should — challenge an incorrect code assignment. If your operations genuinely fit a lower-hazard code, a broker experienced in your trade can formally request reclassification with supporting documentation.
What is a split classification? A split classification applies when a single employee performs work covered by two or more codes (for example, a plumber who also does clerical work). NCCI rules allow payroll to be split between the codes only if the work is clearly separate and time records support the split.
Why Morrow for Workers Comp Classification Review
- Independent agency, multiple carriers. Morrow shops your workers comp across a panel of admitted and specialty carriers [Morrow to confirm carrier list], which means we find the market whose underwriters understand your specific class codes — not just the nearest available insurer.
- Classification audit on every new account. Before binding, we manually review your existing class code assignments against NCCI Scopes and your actual job descriptions. Misclassification errors found before binding save money immediately; errors found at audit cost you money.
- Trade-specific expertise. We routinely place contractors, trucking companies, landscapers, manufacturers, and professional services firms — the trades where class code nuances matter most (governing classification rules, independent contractor exclusions, wrap-up exclusions).
- Audit defense and reconciliation. When your carrier's auditor comes in with a reclassification that inflates your premium, Morrow reviews the audit worksheet, challenges unsupported code assignments, and negotiates on your behalf with documentation.
- Fast certificates and COIs. After binding, certificates of insurance with proper class code references issue same-day for most accounts — no waiting on a carrier service center.
Get a Workers Comp Quote
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Related Pages
- Workers Compensation Insurance for Contractors
- What Is an Experience Modification Rate (EMR)?
- How Much Does Workers Comp Cost?
- Workers Comp for General Contractors
- Certificate of Insurance (COI) — What It Is and How to Get One
Author: Content reviewed by a licensed P&C insurance professional with experience in commercial lines underwriting and workers compensation classification. Published: June 2026 Last updated: June 2026
Sources: - National Council on Compensation Insurance (NCCI) — Basic Manual for Workers Compensation and Employers Liability Insurance - NCCI Scopes of Basic Manual Classifications - California Department of Insurance (CDI) — Workers Compensation Classification System - New York Workers' Compensation Board — Classification and Rating - Insurance Information Institute (III) — Workers Compensation - Occupational Safety and Health Administration (OSHA) — recordkeeping and hazard classification guidance