If you've just been hurt on the job in California, you're about to enter a world of acronyms and legal terms that most people have never heard before. Insurance adjusters, defense attorneys, and claims administrators use this language every day — and they count on the fact that you don't.
AOE/COE is the two-part test California uses to decide if your injury is covered by workers' comp — your injury must arise out of work and happen while you were performing your job duties.
We've recovered over $150,000,000 for injured workers across Southern California. One of the most common reasons people leave money on the table isn't because their case is weak — it's because they didn't understand what the terms in their file actually meant.
This guide gives you plain-English definitions of the 10 terms you will encounter most, with the California Labor Code sections that back them up. Read it before your next appointment, your next phone call with an adjuster, or your first meeting with an attorney.
Here are the 10 workers' comp terms every injured California worker should know:
- AOE/COE — the two-part test that decides if your injury is covered
- TTD / TPD — what you get paid while you can't work (or can only work limited hours)
- PD — the permanent disability rating that determines your long-term benefits
- MMI / P&S — the milestone that triggers your permanent disability rating
- QME / AME — the independent doctors who resolve medical disputes
- MPN — the insurer's approved doctor list and what it limits
- UR / IMR — how treatment gets approved, denied, and challenged
- C&R vs. Stip — the two ways to settle, and why the difference matters enormously
- Apportionment — how insurers use your health history to reduce your award
- DWC-1 — the one form that legally opens your entire case
1. AOE/COE — Arising Out of / In the Course of Employment
AOE/COE is the foundational coverage test in California workers' comp. To receive any benefits, your injury must satisfy both parts: it must arise out of employment (AOE) — meaning it was caused by a work-related risk — AND occur in the course of employment (COE) — meaning it happened while you were doing your job or a job-related activity.
This test comes directly from Cal. Lab. Code §3600, which establishes that liability for workers' comp exists only when both conditions are met. Courts and the WCAB (Workers' Compensation Appeals Board) apply this test to every disputed claim.
Why it matters: Insurance carriers deny claims by arguing one prong fails. A back injury at work almost always meets both — but an injury in the parking lot before clocking in, or a stress claim with no documented workplace trigger, may require a fight on AOE/COE grounds. Knowing this term helps you understand exactly what the insurer is challenging when a denial letter arrives.
Takeaway: If the adjuster says your injury "didn't arise from work" or "didn't happen on the clock," they are attacking AOE/COE. That is a legal dispute, not a final answer — call an attorney before accepting it.
2. TTD / TPD — Temporary Total and Temporary Partial Disability
TTD (temporary total disability) is the wage-replacement benefit you receive when your treating doctor certifies you are completely unable to work because of your injury. It pays two-thirds of your pre-injury average weekly wage under Cal. Lab. Code §4453.
For injuries on or after January 1, 2026, TTD pays up to $1,764.11 per week — two-thirds of your average weekly wage, capped by California law under Cal. Lab. Code §4453.
TPD (temporary partial disability) applies when you can return to work in a limited capacity but earn less than before. The payment bridges the gap between your reduced earnings and your pre-injury wage, also calculated under Cal. Lab. Code §4453.
Both benefits continue until one of three things happens: you return to full duty, you reach MMI/P&S (see Item 4), or the statutory maximum benefit period is exhausted — generally 104 weeks within five years of the injury date under Cal. Lab. Code §4656, with a longer window for certain severe injuries.
Takeaway: TTD is not your full salary — it is two-thirds, capped. If benefits stop before your doctor releases you, that is a problem worth investigating immediately.
3. PD — Permanent Disability
Permanent disability (PD) is the benefit that compensates you for lasting physical limitations after your injury has stopped improving. California rates PD on a scale from 0% to 100% under Cal. Lab. Code §4658, with 100% reserved for workers who are totally and permanently unable to work.
The PD percentage is determined by a doctor's report, your age, your occupation, and the applicable impairment rating guidelines. Once that percentage is set, it translates into a set number of weeks of weekly PD payments — the higher the rating, the more weeks (and the higher the total payout). Workers with PD ratings of 70% or higher may also qualify for a life pension under Cal. Lab. Code §4659.
This is often the biggest single number in your workers' comp case. A one-percentage-point difference in your PD rating can mean thousands of dollars. Insurance-hired doctors frequently rate PD low — this is one of the primary reasons having an attorney matters.
Takeaway: Never accept a PD rating without reviewing whether the underlying medical report accurately captured your limitations. A specialist attorney reviews this as standard practice.
4. MMI / P&S — Maximum Medical Improvement / Permanent and Stationary
MMI (maximum medical improvement) — called Permanent and Stationary (P&S) in California — is the point your treating doctor declares your medical condition has stabilized to the degree that further treatment will not produce meaningful improvement. It is defined under Cal. Lab. Code §4660 as the basis for triggering the permanent disability evaluation process.
MMI, also called Permanent and Stationary, is the point your doctor declares your condition has stabilized — and it is the trigger for calculating your permanent disability rating.
Until your doctor issues a P&S report, you generally continue receiving TTD. Once that report is issued, TTD ends and the process of rating and paying out permanent disability begins. The P&S report is therefore one of the most consequential documents in your entire case — it locks in the medical findings that drive your PD rating and your settlement value.
Takeaway: If your condition is still changing — new symptoms, ongoing surgery, worsening function — you should not be rated P&S yet. A premature P&S declaration can lock in a lower PD rating than you deserve.
5. QME / AME — Qualified Medical Evaluator and Agreed Medical Evaluator
A QME (qualified medical evaluator) is a physician certified by the DWC (Division of Workers' Compensation) to perform independent medical examinations when there is a dispute about your injury, diagnosis, or disability rating. The process for obtaining a QME panel and completing the examination is governed by Cal. Lab. Code §§4060–4062.
A QME is a DWC-certified physician who conducts an independent exam when there is a dispute about your injury or disability under Cal. Lab. Code §§4060–4062 — the QME's findings can directly change your settlement value.
An AME (agreed medical evaluator) is a doctor that both sides — you and the insurance carrier — mutually select instead of going through the DWC's random QME panel process. AMEs are often used when both parties want to avoid the panel lottery and instead choose a physician both sides respect.
The QME or AME report often determines your final PD rating and whether disputed injuries are accepted. These exams are not neutral — you should prepare for them carefully, ideally with an attorney's guidance.
Takeaway: The QME or AME report can add or subtract tens of thousands of dollars from your case. Never walk into one of these exams without understanding what is at stake.
6. MPN — Medical Provider Network
An MPN (medical provider network) is an employer- or insurer-approved list of doctors authorized to treat your work injury. California law under Cal. Lab. Code §4616 allows employers to establish MPNs, and if your employer has a valid MPN in place, you are generally required to treat within it — except for emergency care and certain pre-designated physician situations.
The practical impact: the insurer effectively controls your initial pool of treating doctors. MPN doctors are not necessarily biased against you, but they work with insurance carriers regularly. You have the right to a second and third opinion within the MPN if you disagree with your treating doctor's conclusions.
If your employer does not have a valid MPN, you have broader rights to choose your own doctor — or to pre-designate your personal physician before an injury occurs under Cal. Lab. Code §4600.
Takeaway: If you feel your MPN doctor is not listening to you or is minimizing your injury, you have options — a second opinion within the MPN, or a challenge to treatment decisions through IMR (see Item 7).
7. UR / IMR — Utilization Review and Independent Medical Review
UR (utilization review) is the process insurance carriers use to approve or deny your doctor's recommended treatment — surgery, physical therapy, prescription medication, imaging studies, and more. The process is governed by Cal. Lab. Code §4610, which requires the insurer to act within set timeframes and use medically recognized criteria.
When UR denies a treatment your doctor says you need, you can challenge it through IMR (independent medical review) — an independent process administered by the DWC in which a neutral physician reviews the denial. Under Cal. Lab. Code §4610.5, the IMR decision is binding on both parties.
IMR overturns UR denials more often than most injured workers realize. The key is filing the IMR request within 30 days of the final UR denial — missing that window forfeits your right to challenge.
Takeaway: A UR denial is not the end. File your IMR request within 30 days and get your attorney involved immediately — delayed treatment can also worsen your condition and your case value.
8. C&R vs. Stip — Compromise and Release vs. Stipulated Award
These are the two ways your California workers' comp case can close, and choosing between them is one of the most consequential decisions in your entire claim.
A Compromise and Release (C&R) is a lump-sum settlement that closes your case completely — including your right to future medical treatment for the injury. Once approved by a WCAB judge, the C&R is final. You receive a single payment, and the case is done.
A Stipulated Award (Stip) — formally a Stipulation with Request for Award — resolves the permanent disability portion of your case while keeping future medical care open. You receive weekly PD payments over time, and the insurance carrier remains responsible for treating your injury for the rest of your life if necessary.
A Compromise and Release closes your entire case in a lump sum, including future medical care, while a Stipulated Award keeps future medical treatment open — choosing wrong can cost you tens of thousands of dollars in future care.
Both settlement types require WCAB judge approval under Cal. Lab. Code §5001. For more on how these two options compare in practice, see our detailed breakdown at /blog/stipulated-award-vs-compromise-and-release.
Takeaway: If you have an ongoing condition requiring surgery or long-term care, a C&R that sounds like a large check today may leave you paying out of pocket for treatment for decades. Never choose between C&R and Stip without reviewing your medical future with an attorney.
9. Apportionment — Splitting Cause Between Work and Pre-Existing Conditions
Apportionment is how California law allows the insurance carrier to reduce your permanent disability award by attributing part of your disability to causes other than your current work injury — such as a prior injury, a pre-existing degenerative condition, or a non-industrial health issue.
It is governed by Cal. Lab. Code §4663, which requires the apportionment analysis to be based on "substantial medical evidence" — meaning a doctor must provide a reasoned, medically grounded explanation for what percentage of your disability is work-related versus pre-existing.
Apportionment under Cal. Lab. Code §4663 lets the insurance carrier reduce your permanent disability payment by the share they attribute to pre-existing conditions — it is one of the most common tools used to lower settlements.
For example: if you have a prior back condition and suffer a new work-related back injury, the insurer's doctor may opine that 40% of your current disability is from the prior condition — cutting your PD award by 40%. This apportionment determination is frequently contested, and the quality of the medical evidence on both sides matters enormously.
Takeaway: If you have any prior injuries or pre-existing conditions and an insurance doctor is rating your case, expect an apportionment argument. An attorney can challenge apportionment opinions that are not medically supported.
10. DWC-1 — The Claim Form That Opens Your Case
The DWC-1 is the official California workers' compensation claim form. Filing it is the act that legally opens your workers' comp case. Under Cal. Lab. Code §5401, your employer must provide you with the DWC-1 within one working day of learning about your injury — and once you file it, your employer's insurer must authorize up to $10,000 in medical treatment while investigating whether to accept your claim.
Filing the DWC-1 claim form under Cal. Lab. Code §5401 is the act that legally opens your workers' comp case and entitles you to up to $10,000 in medical treatment while your claim is being investigated.
The DWC-1 also starts the clock on important deadlines. California generally gives injured workers one year from the date of injury to file a workers' comp claim under Cal. Lab. Code §5405. Failing to report your injury to your employer within 30 days of the injury can put your benefits at risk under Cal. Lab. Code §5400.
You can download the DWC-1 directly from the DWC website, or your employer is required to have it on hand.
Takeaway: Do not wait to file the DWC-1. That one form unlocks medical treatment, starts your legal protection, and preserves deadlines you cannot get back.
Know the Terms — Then Call a Specialist
Understanding these 10 terms puts you ahead of most injured workers who walk into the system alone. But knowing the vocabulary and knowing how to use it in your specific case are two different things.
Insurance carriers have adjusters, nurse case managers, defense attorneys, and QME doctors working every angle of your claim. You deserve the same quality of legal representation as any corporation — and that starts with a phone call.
We've recovered over $150,000,000 for injured workers across Southern California. Our workers' compensation attorneys handle every part of your case — from the DWC-1 through the final C&R or Stip — with no fee unless we win.
Call (818) 794-9947 for a free case review. No fee unless we win. Available in English and Spanish.
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Frequently Asked Questions
What does AOE/COE mean in a California workers' comp claim?
AOE/COE stands for "arising out of and in the course of" employment. Under Cal. Lab. Code §3600, both parts must be satisfied for your injury to be covered by workers' comp. AOE means the injury was caused by a work-related risk; COE means it happened while you were performing your job. When insurers deny claims, they often argue one prong isn't met — that denial is challengeable.
What is a QME and when do I need one?
A QME (qualified medical evaluator) is a DWC-certified physician who conducts an independent medical examination when there is a dispute about your injury, your diagnosis, or your permanent disability rating. The process is governed by Cal. Lab. Code §§4060–4062. You typically need a QME when your treating doctor's findings are disputed by the insurance carrier or when you disagree with an offered PD rating.
What is the difference between a C&R and a stipulation in workers' comp?
A Compromise and Release (C&R) settles your entire case for a lump sum and closes out your right to future medical treatment. A Stipulated Award (Stip) resolves your permanent disability in weekly payments while keeping future medical care open. The right choice depends on your medical condition, prognosis, and financial needs — and it is one of the most important decisions in your case.
What is apportionment and can I fight it?
Apportionment under Cal. Lab. Code §4663 is the process of reducing your PD award based on the percentage of disability attributed to non-work causes, such as pre-existing conditions. It must be based on substantial medical evidence — a reasoned medical opinion, not a guess. Yes, you can fight an apportionment determination if the medical opinion supporting it is inadequately reasoned or contradicted by your treating doctor's findings.
When should I file the DWC-1 claim form?
File the DWC-1 as soon as possible after a work injury. Your employer must provide it within one working day of learning about your injury under Cal. Lab. Code §5401. You have up to one year from the date of injury to file under Cal. Lab. Code §5405, but waiting creates risk — and you lose the immediate $10,000 in authorized medical treatment the DWC-1 triggers. Report your injury to your employer within 30 days to protect your benefits.
What happens if UR denies my treatment?
If utilization review (UR) denies a treatment your doctor recommended, you have 30 days to request independent medical review (IMR) under Cal. Lab. Code §4610.5. An independent physician then reviews the denial, and that decision is binding on the insurer. IMR overturns UR denials in a meaningful number of cases — but missing the 30-day window forfeits your right to challenge.
What is the difference between TTD and TPD?
TTD (temporary total disability) pays two-thirds of your average weekly wage when you are completely unable to work, up to the 2026 maximum of $1,764.11 per week. TPD (temporary partial disability) applies when you can return to work in a limited capacity but earn less than your pre-injury wage — it bridges the income gap. Both are governed by Cal. Lab. Code §4453.
What does MMI or Permanent and Stationary mean?
MMI (maximum medical improvement), called Permanent and Stationary (P&S) in California, means your treating doctor has determined your condition has stabilized and further treatment will not produce significant improvement. This triggers the permanent disability rating process. Until P&S is declared, you generally continue receiving TTD. A premature P&S declaration can lower your PD rating, so it is important your doctor accurately reflects your ongoing limitations.
Reviewed by Minas Nordanyan, CA Bar #296806 — Workers' Compensation Specialist, Nordanyan Law. Last legal review: June 2026.