Workers' compensation premium is one of the few insurance costs a business owner can move in a measurable way. Rates are set by the state or the carrier, but the inputs that drive your bill (how your work is classified, how many hours or how much payroll you report, and what your claims history looks like) are largely within your control. This guide focuses on Washington, where most employers buy coverage from the Department of Labor & Industries (L&I), and notes where the approach differs in other states.
How your premium is built
Washington is one of four monopolistic states, along with Ohio, North Dakota and Wyoming, where employers must buy workers' compensation from the state fund rather than a private carrier. L&I calculates an individual premium rate from three things: your risk classifications, the base rates for each classification, and your business's experience factor.
For each classification, L&I multiplies the experience factor by the sum of the Accident Fund, Medical Aid Fund and Stay at Work base rates, then adds the Supplemental Pension Fund base rate. Unlike most states, Washington charges per hour worked, not per dollar of payroll. Employees share the cost: the Medical Aid, Stay at Work and Supplemental Pension portions are split equally between employer and worker, while the Accident Fund is paid entirely by the employer. L&I estimates that workers pay roughly a quarter of total premium.
In most other states, premium is payroll (per $100) times a class rate, adjusted by an experience modification factor. Under the NCCI experience rating plan used in many states, the mod compares your actual losses to the losses expected for a business of your size and type. Our article on the experience modification rate walks through that calculation.
Step 1: Get classification and reporting right
The fastest savings are often errors corrected. Classification drives your base rate, so it is worth confirming that each risk class assigned to your account still matches the work you actually do.
- Review your risk classes every year. If your operations have changed (you stopped field work, added a shop, moved staff to clerical roles), ask L&I to review the account.
- Report hours by the class the work falls in. Where the rules allow hours to be split between classifications, keep the time records that support the split. Without records, hours tend to default to the higher-rated class.
- Keep owner and officer coverage decisions current. Whether owners and corporate officers are covered affects reported hours; confirm the elections on file still reflect what you want.
- Prepare for audits. Clean payroll and timekeeping records make an audit routine. See premium audit preparation for a checklist.
Step 2: Manage your experience factor
The experience factor is where your safety and claims results show up in price. L&I recalculates it every year for each business. The experience period is the oldest three of the four fiscal years before the effective date of the rates, so each claim affects your premium for three calendar years. L&I weights your actual losses according to credibility (larger employers' own results count more), and it replaces the actual cost of a fatal claim with an average fatal claim cost.
Two practical consequences follow. First, the claims you prevent or close well this year pay off over several renewals, not just one. Second, small, frequent claims matter. Under NCCI's plan in other states, losses are split into primary and excess portions, with primary losses receiving full weight and excess losses partial weight; where the experience rating adjustment applies, medical-only claims are reduced by 70% in the calculation, which rewards getting injured workers proper treatment early before a claim turns into lost time.
| Lever | What it affects | Where to start |
|---|---|---|
| Injury prevention | Claim frequency and severity | Job hazard analysis, new-hire training, safety committee |
| Prompt reporting | Claim cost and duration | Same-day supervisor report, clear injury reporting steps |
| Return to work | Time-loss costs | Written light-duty job offers, Stay at Work |
| Claim follow-up | Reserves and closure | Regular contact with the claim manager and the worker |
| Classification review | Base rate | Annual review of risk classes and hours reporting |
L&I also offers a claim-free discount to employers with low claim costs. Eligibility depends on expected losses, not headcount.
Step 3: Use Stay at Work for light duty
Getting an injured employee back to productive, medically approved work is usually the single biggest lever on claim cost. Washington's Stay at Work program reimburses part of the cost of doing it. For injuries on or after January 1, 2025, L&I reimburses 50% of the worker's base gross wages (excluding tips, bonuses and commissions) for up to 120 days worked, capped at $25,000, plus up to $5,000 for tools and equipment, $2,000 for training and $1,000 for clothing needed for the light-duty job. For injuries before 2025, the older limits apply: up to 66 days and $10,000 in wages, $2,500 for tools, $1,000 for training and $400 for clothing.
Paperwork matters. Expenses must be necessary for the light-duty job and purchased on or after the job offer. Starting January 1, 2026, L&I asks employers to submit reimbursement requests through My L&I; fax and mail submissions are being phased out.
A written transitional-work program makes this repeatable instead of improvised. Our guides to return-to-work programs and modified duty cover how to build job descriptions your workers' doctors can approve.
Step 4: Prevent the injuries that drive cost
No premium strategy outperforms fewer injuries. Focus on the tasks that produce your claims, not generic safety posters. Pull three years of claims, group them by body part, task and tenure, and you will usually find a short list of causes: lifting and material handling, slips and falls, vehicle incidents, and, for many employers, injuries to workers in their first months on the job.
Analyze the job
Break high-risk tasks into steps and fix the hazard at each step. See job hazard analysis.
Train new hires early
Check whether your claims cluster in employees' first months. If they do, make the first week count with task-specific training.
Give it a team
An active safety committee keeps attention on near-misses and follow-through.
Step 5: Consider the Retrospective Rating program
Retro is an optional L&I program that lets employers share in the results of their own safety and claims management. Any employer in good standing can participate, individually or through a Retro group. A Retro coverage period is 12 months and can begin in any calendar quarter. About nine months after the period ends, L&I compares actual claims experience to the standard premium; that evaluation is repeated three times, about 12 months apart. If results are better than expected, you may receive a partial refund. If they are worse, you may owe an assessment, up to a limit you select in advance.
Retro is not free money. It rewards employers who already manage claims actively. Understand the assessment risk, the group's fees and its claims-management requirements before you enroll.
Plan for rate changes and coverage gaps
Base rates change every year. In fall 2026, L&I proposed a 4.9% average increase for 2027, about $1.44 a week per full-time employee, shared between employers and workers, with 311 of the state's 326 risk classes facing higher base rates. Your own change will depend on your classes and your experience factor, so check L&I's adopted rates when they are published and budget accordingly.
Two coverage issues are worth checking at the same time:
- Stop gap (employers liability). State-fund coverage in monopolistic states does not include employers liability. Businesses usually add stop gap coverage to their general liability policy to respond to certain employee injury lawsuits that fall outside the workers' comp system. Forms and limits vary by carrier.
- Work outside Washington. If employees travel or work in other states, requirements differ by state. Confirm how out-of-state work is covered before it starts, not after an injury.
Our workers' compensation page covers how we help clients outside Washington with carrier-placed coverage, and our claim management guide goes deeper on keeping open claims on track.
When to call a broker
Talk with us if your experience factor or mod has risen two years in a row, if you are unsure your risk classes fit your work, if you are weighing a Retro group, or if you are expanding into another state. As a broker, we review classifications, claims and coverage together and help you decide which levers are worth pulling first. Premium outcomes depend on your claims, classifications and the rates in effect; no strategy guarantees a reduction.
Sources
- Washington L&I — How L&I calculates the premium rate for an individual business
- Washington L&I — Unique premium rating features in Washington
- Washington L&I — Experience rating
- Washington L&I — Stay at Work
- Washington L&I — About Retrospective Rating
- Washington L&I — Proposed 2027 workers' comp rates
- NCOIL / NCCI — Basics of Experience Rating
- The Hartford — Monopolistic states for workers' compensation