Guides
Workers' compensation insurance: how it works
What workers' comp pays, who must carry it, how premium is built from payroll, class codes and the experience mod, and what the policy's three parts do.
Workers' compensation insurance pays medical bills and a share of lost wages for employees hurt or made ill by their jobs, regardless of who was at fault. In exchange, the employee generally gives up the right to sue the employer for the injury. Nearly every state requires employers to carry it once they have employees, and the premium is driven by payroll, job classification and your own claims history.
The bargain behind the system
workers' compensation is a no-fault trade. Before these laws, an injured worker had to sue and prove the employer was negligent, which was slow, uncertain and expensive for both sides. State statutes replaced that with guaranteed benefits that do not depend on fault, paid by the employer or its insurer. The worker gets prompt medical care and wage replacement. The employer gets what lawyers call exclusive remedy: the comp claim is the injury claim, and a negligence suit against the employer is barred in most circumstances.
Exclusive remedy has exceptions that vary by state, such as intentional harm, an uninsured employer (who loses the protection in many states), and claims against third parties who are not the employer. A forklift manufacturer or a negligent driver from another company can still be sued by the injured worker, and the comp carrier will usually assert a lien through subrogation against any recovery.
Because every state writes its own act, benefit levels, waiting periods, filing deadlines, who counts as an employee and how disputes are resolved all differ. Nothing in this guide substitutes for your state's statute or your state's workers' comp agency. For a state-by-state view, see workers' comp requirements by state: who must carry it and the workers' comp and benefits requirements by state.
What the policy pays
Benefits fall into a few standard buckets, with amounts and durations set by state law:
- Medical benefits. Treatment related to the injury, usually with no deductible and no copay for the worker, subject to the state's fee schedule and rules about who chooses the doctor.
- Temporary disability. Wage replacement while the employee cannot work, commonly about two-thirds of the average weekly wage up to a state maximum, usually after a short waiting period.
- Permanent disability. Payment when an employee is left with a lasting impairment, calculated under state formulas that vary widely. Terms like maximum medical improvement and permanent partial disability drive this stage.
- Vocational rehabilitation. Retraining or job placement help in many states when the worker cannot return to the old job.
- Death benefits. Burial costs and payments to surviving dependents.
The employer does not pay these out of pocket under a policy. The carrier handles the claim, sets the reserve and pays the benefits. Your job is to report promptly, document the incident and help the employee return to modified work. The mechanics are in the workers' comp claims process for employers, and early return-to-work is covered in return-to-work programs: how to build one.
The three-part standard policy
Most states use the NCCI Workers Compensation and Employers Liability Insurance Policy, form WC 00 00 00, written by NCCI and adopted with state variations. Independent bureaus in states such as California, New York, Pennsylvania and Michigan have their own forms or endorsements, and carriers may attach state amendatory endorsements. The standard form is organized as follows:
| Part | What it does |
|---|---|
| Part One, Workers' Compensation | Promises to pay the benefits the law requires, with no dollar cap, in the states listed in Item 3.A of the information page |
| Part Two, Employers Liability | Pays damages for injuries that fall outside the comp system, such as third-party-over suits and some dual-capacity claims, up to stated limits |
| Part Three, Other States | Gives coverage if work begins in a state not listed in Item 3.A, for states listed in Item 3.C |
The later parts cover your duties after an injury, the premium rules (including audits) and conditions such as cancellation. Part Two is separate from Part One and carries its own limits, which is why it has its own guide: employers' liability insurance. If your people work across state lines, check how other states coverage is written and read employees in several states: other-states coverage and multistate workers' comp.
Who has to carry it
The short answer is nearly every employer with employees, but the threshold is state law and it is not uniform. Some states require coverage from the first employee. Others set a headcount threshold, often with different rules for construction or agriculture. Texas is the one state where most private employers may legally decline comp, a choice described in texas nonsubscribers: opting out of workers' comp. Corporate officers, LLC members and sole proprietors may be required, optional or excludable, depending on the state (can owners and officers exclude themselves from workers' comp?).
Four states are monopolistic: North Dakota, Ohio, Washington and Wyoming. Private insurers cannot write comp there for in-state workers, so employers buy from the state fund or, where allowed, qualify to self-insure. In Wyoming, coverage is mandatory only for extra-hazardous work listed in statute. Employers' liability is not part of the state-fund policy in those states and is bought separately as stop gap coverage. The details are in Monopolistic state funds: workers' comp in ND, OH, WA and WY. See also Ohio for how one monopolistic state works day to day.
Misclassifying employees as independent contractors does not remove the obligation. Auditors and state agencies look at the relationship, not the label (independent contractors and workers' comp: the misclassification risk). Penalties for going uninsured are serious and state-specific: stop-work orders, fines tied to the premium you should have paid, and, in some states, criminal charges. California and Florida illustrate the range; their guides (California, Florida) lay out the rules.
How premium is built
Comp is priced on a rate per $100 of payroll, charged by job classification, then adjusted. In outline:
- Each employee's payroll is assigned to a class code that describes the work.
- Payroll divided by 100 is multiplied by the class rate.
- The sum is multiplied by your experience modification, the experience modification rate, which compares your history with similar employers.
- Credits, debits, schedule rating, state surcharges and fees are applied, and a minimum premium may apply.
- After the term, an audit trues up the estimate to actual payroll.
Say a hypothetical roofing company has $200,000 in roofer payroll and $70,000 in clerical payroll. NCCI's own training example uses rates of $63.171 per $100 for roofing and $0.750 for clerical, which produces $126,867 before the mod and $158,584 with a 1.25 mod. The point of the example is not the rates, which belong to one illustration, but the shape: classification dominates, and a mod above 1.00 multiplies the whole bill. The full process is in how workers' comp premiums are calculated, class assignment is in workers' comp class codes and why they matter, and the mod is in The experience modification rate (EMR) explained. You can model your own figures with the workers' comp premium calculator.
Where the policy comes from
Employers buy comp in the voluntary market from private carriers, through a state fund in states that have a competitive one, or from the residual market if no carrier will write them. The residual market is the assigned risk plan, explained in assigned risk and residual markets for workers' comp. Large employers can use deductible or self-insured structures (large deductible workers' comp programs: how they work and what they cost, self-insuring workers' comp: requirements and trade-offs). A professional employer organization can also bundle comp with payroll and HR, with co-employment consequences covered in PEOs and workers' comp: co-employment explained.
NCCI's State of the Line report for 2026 put the private carrier workers' comp combined ratio at 91 for 2025, up from 86 in 2024, which means carriers were still earning an underwriting profit (Business Insurance's report). Trade coverage of the same report noted falling loss costs and rate levels. A soft rate environment is a good time to review classifications and your mod rather than only chase price. Trends are tracked in workers' comp trends: frequency, severity and rates in 2026.
What to do as an employer
A practical checklist for a business that has just hired its first employee or is reviewing coverage:
- Confirm in your state whether you must carry comp and whether owners count toward the threshold.
- Ask your broker to confirm every state where employees work is listed in Item 3.A or 3.C.
- Review the class codes and payroll estimates before binding, not at audit.
- Keep payroll records, subcontractor certificates and 1099 backup ready for the auditor (premium audits: how they work and how to prepare).
- Post the required notices and know your state's injury reporting deadline (reporting a workplace injury: what employers must do).
- Build a safety and return-to-work process, since your own claims set your future mod (how to lower your workers' comp costs).
Key takeaways
- Workers' comp is no-fault coverage for job injuries that also generally bars the employee from suing the employer; the rules differ in every state.
- The standard NCCI policy has Part One (statutory benefits, no dollar limit), Part Two (employers liability, with limits) and Part Three (other states).
- North Dakota, Ohio, Washington and Wyoming are monopolistic; Texas lets most private employers opt out.
- Premium is payroll times a class rate times your experience mod, trued up at audit, so classification and claims history are the levers you control.
- Misclassifying workers or skipping coverage exposes you to stop-work orders, penalties and uninsured-claim liability.