Pre-Existing Condition and Workers' Comp: What's Actually Covered

Every insurance carrier's first move when they see your workers' comp claim is to pull your old medical records.

If you've ever seen a chiropractor, gone to the ER, had an MRI, or mentioned back pain at a physical, it's in there. And the adjuster will use it. The denial letter will say something like: "Claimant has documented history of lumbar strain from 2019 — current complaint appears to be continuation of pre-existing condition."

Here's the thing they don't put in the letter: pre-existing conditions are covered by workers' comp. Every state. The question isn't whether you had a prior problem; it's whether work made it worse. That's the whole fight.

The Law Is Actually on Your Side Here

Workers' comp statutes in all 50 states cover what's called "aggravation" of pre-existing conditions. The logic is old and well-established — your employer takes you as you are. If you came in with a bad back and work made it worse, work is responsible for the "worse" part. This is sometimes called the eggshell plaintiff rule, borrowed from tort law: the defendant is liable for the full harm even if the plaintiff was unusually fragile.

What this means in practice: the carrier cannot simply point at old records and walk away. They have to prove your work activity contributed nothing new to your current condition. That's a hard thing to prove, and judges know it.

What Carriers Actually Look For

When an adjuster pulls your records, they're scanning for five things: any prior imaging of the same body part, any prior doctor visit with the same complaint, any gym or sports injury you casually mentioned to a provider, any workers' comp claim from a previous employer, and any personal injury settlement (car accident, slip-and-fall) involving that body part.

Any one of these becomes the basis for a pre-existing condition denial. A chiropractor visit from eight years ago where you said "my back feels tight" can show up in a denial letter as "documented chronic lumbar complaints." It's almost comical how aggressive the framing gets.

The good news: most of these flags are weak when examined closely. A single chiropractor visit years ago doesn't establish an ongoing condition. An MRI from 2015 showing mild disc bulges is not the same as the 2026 MRI showing a large herniation with nerve root compression. The differences are what your case is built on.

The Three Pieces of Evidence That Win Aggravation Claims

Aggravation claims come down to documentation, and specifically three kinds of it.

A clear baseline. You need records showing what your body part looked like before the work injury. Old MRI reports, old exam notes, old pain ratings. This sounds bad — why would you want to hand the carrier evidence of a prior condition? Because the baseline is also your floor. If your 2020 MRI showed mild degenerative disc disease and your 2026 MRI shows a full L4-L5 herniation with radiculopathy, those are different problems. The baseline proves it.

A documented change. New imaging, new exam findings, new restrictions, new pain levels that post-date the work event. The closer in time the new documentation is to the work incident, the stronger. An MRI taken within 2 weeks of the work injury showing a finding that wasn't on your 2020 MRI is close to a knockout. An MRI taken 6 months later is still useful but less dispositive.

A causation opinion from your treating doctor. This is the piece most workers miss, and it's the single most important document in an aggravation case. You need a short written statement from your doctor saying, in so many words: "The work activity on [date] caused or materially aggravated [specific condition]. The current symptoms would not exist, or would be meaningfully milder, without the work injury."

Doctors don't write this naturally. They write in clinical shorthand that satisfies medical records but doesn't satisfy workers' comp judges. You have to ask for the opinion specifically, and often you have to ask twice. Some treating doctors will do it as part of a regular visit. Some require a dedicated causation evaluation, which is a separate appointment and sometimes a separate bill.

A Real Example of How This Plays Out

Consider a warehouse worker, age 52, with a 2021 MRI showing mild degeneration at L5-S1 — one visit to a chiropractor, no follow-up, back to work. In March 2026 he's lifting a 70-pound box when he feels a pop and immediate sharp pain radiating down his right leg. New MRI two weeks later: L5-S1 herniation with nerve root impingement, L4-L5 annular tear that wasn't visible in 2021, active radiculopathy confirmed by EMG.

The carrier denies, citing the 2021 chiropractor visit. "Pre-existing lumbar condition." Standard letter.

His attorney gets the treating orthopedist to write a one-paragraph causation opinion: "Patient's March 2026 MRI demonstrates findings not present on prior imaging. The annular tear and nerve root impingement are acute changes directly attributable to the lifting event. Patient's mild degenerative changes from 2021 would not produce the current radicular symptoms. The work injury is the material cause of the current condition."

At the hearing, the judge sided with the worker. Final settlement: $127,000. If he had handled this himself without getting the causation opinion, he probably settles for $15,000 on a nuisance-value basis or loses outright.

That causation paragraph is worth six figures.

If You're Offered an IME, Be Careful

An Independent Medical Examination (IME) is a carrier-selected doctor who examines you specifically to dispute your claim. They are not independent in any meaningful sense — the carrier picks them, pays them, and sends them cases over and over. IME doctors who consistently find "no work relation" get more referrals.

In aggravation cases, IMEs are the carrier's strongest weapon. The IME will almost always conclude either (a) the current condition is purely a continuation of pre-existing disease or (b) the work event caused a temporary aggravation that has since resolved. Both conclusions get your benefits cut off.

You can't refuse an IME without losing your claim, but you can prepare. Don't exaggerate symptoms — IME doctors are trained to spot inconsistencies and will document them harshly. Don't minimize either. Describe your pain and limitations accurately and consistently with what you've told your treating doctor. Bring the exact list of medications you're on. If you've seen ten other providers, know the dates and diagnoses.

After the IME, your attorney can request the report, rebut it with your treating doctor's counter-opinion, and sometimes get a second IME from a more neutral physician. This is routine in pre-existing condition cases.

Settlement Math for Aggravation Cases

Here's where aggravation claims get frustrating: even when you win, you usually win less than a fresh injury would pay.

Carriers and judges both discount aggravation settlements for the pre-existing baseline. The theory is that some portion of your current condition would have existed anyway — so workers' comp shouldn't pay for all of it. The discount is rarely quantified precisely, but roughly:

A fresh, clean back injury with surgery might settle in the $90K-$120K range in an average state. The same injury with a documented 5-year history of prior back issues typically settles for $55K-$80K. The same injury with a prior lumbar fusion from a car accident might settle for $30K-$50K — the carrier argues most of the current disability predates the work event.

This discount is negotiable. Strong causation evidence shrinks it. Weak evidence grows it. A treating doctor who says "100% of the current condition is work-related" gets you paid close to a fresh-injury number. A treating doctor who says "the work event accelerated an underlying condition by 2-3 years" gets you paid at a steep discount.

Disclosure Matters More Than You Think

One unforced error in pre-existing condition cases: failing to disclose.

When you fill out the claim form or get deposed, you'll be asked about prior injuries and treatment. Answer completely and accurately. The carrier will pull your records regardless, and if they find something you didn't disclose, they'll amend the denial to include a fraud allegation. Fraud denials are much harder to beat and can expose you to criminal charges in some states.

Full disclosure combined with a strong causation opinion beats strategic omission every time. Your attorney knows how to present a prior history in the best light. The carrier can't use disclosure against you — it's expected. They can absolutely use non-disclosure against you, and they will.

The Bottom Line

A pre-existing condition denial is not a real obstacle most of the time. It's the carrier's default move, deployed at scale because most workers give up when they see it.

What beats it: baseline evidence (old records showing your prior state), change evidence (new imaging or findings after the work event), and causation evidence (a clear written opinion from your treating doctor linking the work activity to the current condition). Miss any of the three and the claim gets harder. Nail all three and most aggravation claims settle rather than going to hearing, because the carrier knows they'll lose.

If you've been denied on pre-existing grounds, don't accept it. Get the records together, get the doctor's opinion in writing, and talk to a workers' comp attorney. The consultation is free. The math almost always works in your favor.