Workers compensation is a unique corner of property and casualty insurance because it's built on a legal bargain rather than ordinary liability. It covers employees who are injured on the job, and it's mandatory for most employers. This guide explains the exclusive remedy concept, the statutory benefits provided, the difference between Coverage A and Coverage B, and how premiums are calculated using classifications and the experience modification factor.

The grand bargain behind workers compensation

Workers compensation exists because of a historic compromise often called the "grand bargain" or exclusive remedy doctrine. Here's the deal:

• Employees give up their right to sue their employer over a workplace injury.
• In exchange, employers provide guaranteed benefits for job-related injuries and illnesses regardless of fault.

This is the exclusive remedy concept: workers comp is the employee's sole remedy against the employer for an on-the-job injury. The injured worker doesn't have to prove the employer was negligent, and the employer is protected from most lawsuits. Benefits flow on a no-fault basis—even if the employee was careless, they're still covered.

What "arising out of and in the course of employment" means

Benefits apply to injuries and illnesses that are work-related, summarized by the phrase "arising out of and in the course of employment" (AOE/COE). This includes:

• Sudden accidents (a fall, a cut, a crushed hand).
• Occupational diseases that develop over time from job exposure (hearing loss, repetitive stress, lung disease).

It generally excludes injuries from off-the-job activities, intoxication, or intentional self-harm.

Statutory benefits

Workers compensation benefits are statutory—meaning they're set by law, not negotiated in the policy. The benefit categories are consistent across the country even though exact amounts differ by jurisdiction (and exams keep this national/general). The main categories:

• Medical benefits — covers reasonable medical care related to the injury, typically with no dollar limit and no deductible.
• Disability income (lost wages) — replaces a portion of lost income, divided into four classic types:
  • Temporary Total Disability (TTD) — fully unable to work for a time, expected to recover.
  • Temporary Partial Disability (TPD) — can do some work temporarily at reduced capacity.
  • Permanent Total Disability (PTD) — never able to return to gainful work.
  • Permanent Partial Disability (PPD) — a lasting impairment but still able to work in some capacity.
• Rehabilitation benefits — medical and vocational rehab to help the worker recover or retrain.
• Death benefits — payments to surviving dependents plus a burial allowance.

Coverage A vs. Coverage B

The workers compensation policy has two distinct insuring agreements, and the exam loves to compare them.

• Coverage A — Workers Compensation pays the statutory benefits the law requires. Because benefits are set by statute, Coverage A has no dollar limit—the insurer pays whatever the law mandates.
• Coverage B — Employers Liability covers the employer's legal liability for work-related injuries that fall outside the statutory system—for example, certain lawsuits a worker or third party can still bring. Unlike Coverage A, Coverage B has stated dollar limits (it's a liability coverage with limits per accident, per disease, etc.).

A simple way to remember it: Coverage A = the benefits the law guarantees; Coverage B = the lawsuits that slip through the cracks.

There's also a standard Part Three (Other States Insurance) that extends coverage to additional states listed on the policy, and the policy excludes federal acts (like the U.S. Longshore and Harbor Workers' or the Federal Employers' Liability Act), which require separate coverage.

How premiums are calculated

Workers comp premiums are based on payroll, not on a flat amount, because payroll is a good proxy for exposure to injury.

• Premium basis = payroll, usually expressed per $100 of payroll.
• Each type of work is assigned a classification code with a rate reflecting its hazard. Office clerical work has a low rate; roofing has a very high rate.
• Basic formula: (Payroll ÷ 100) × Class Rate = Manual Premium.

The experience modification factor (Mod)

The experience modification factor—the "experience mod" or "mod"—adjusts an employer's premium based on its past loss history compared to others in the same classification.

• A mod of 1.0 is average/expected.
• A mod above 1.0 (e.g., 1.25) means worse-than-average losses → higher premium (a debit).
• A mod below 1.0 (e.g., 0.85) means better-than-average losses → lower premium (a credit).

The mod rewards safe employers and penalizes those with frequent claims, giving businesses a financial incentive to prevent injuries.

Premium audit

Because final payroll isn't known until the year ends, the policy is auditable. The insurer estimates premium at the start, then performs a premium audit afterward to adjust to the actual payroll—issuing a refund or an additional bill.

Key terms at a glance

Common exam traps

• Workers comp is no-fault—the employee does not have to prove employer negligence.
• Coverage A has NO dollar limit (statutory); Coverage B HAS limits (liability).
• The premium basis is payroll, expressed per $100—not number of employees or revenue.
• An experience mod below 1.0 lowers premium; above 1.0 raises it.
• Exclusive remedy generally prevents the employee from suing the employer for the workplace injury.
• Occupational diseases are covered, not just sudden accidents.
• Workers comp premium is estimated then audited, so the final bill can change.
• Federal workers (longshore, railroad) need separate coverage, not the standard state policy.

Quick recap

• Workers compensation is a no-fault, exclusive remedy system: employees get guaranteed benefits, employers get protection from most lawsuits.
• Benefits are statutory: medical, disability income (TTD/TPD/PTD/PPD), rehabilitation, and death benefits.
• Coverage A pays statutory benefits with no dollar limit; Coverage B (Employers Liability) covers lawsuits and has limits.
• Premium is based on payroll per $100 times a classification rate for each job's hazard.
• The experience mod adjusts premium up or down based on loss history (1.0 is average).
• Final premium is set by a premium audit after the policy period.
• Injuries must arise out of and in the course of employment, including occupational diseases.