“I hurt the same body part at my new job.”

What is actually happening

Two claims, potentially two carriers, and a dispute over how much of your current disability belongs to each.

The old employer’s carrier will say the new injury caused it. The new employer’s carrier will say you were already damaged. Both arguments are made simultaneously, and if you only filed one claim, only one of them is in the room.

The rules they will be arguing about

§ 4663 — apportionment to causation. Each is liable only for the portion its injury caused, and any opinion assigning a percentage must explain how and why. Under EscobedoEscobedo The en banc decision requiring an apportionment opinion to explain how and why. A percentage without reasoning is not substantial evidence., a percentage without reasoning is not substantial evidenceSubstantial evidence The standard a medical opinion must meet to support a finding., and a great many are exactly that.

§ 4664(b) — if there was a prior award of permanent disabilityPD Permanent Disability. Compensation for lasting impairment. A different and much lower weekly rate — 2026 maximum $290/week., that disability is conclusively presumed to still exist. Conclusively — it is not open to rebuttal. Which is why the first question is always whether there was an actual award, rather than a Compromise and ReleaseC&R — Compromise and Release A lump sum that closes future medical treatment permanently. that never produced one; § 4664(b) is asserted far more often than it applies. Note what (b) does not say: there is no “same region” limb in it.

§ 4664(c) is the separate rule people run together with it — the accumulation of all permanent disability awards for any one region of the body may not exceed 100 percent over your lifetime, with the regions defined in the statute. That is a lifetime cap by region; (b) is a presumption about a prior award.

§ 5500.5 — if any part of this is cumulative rather than a single event, liability is confined to a defined exposure window, and you may proceed against one liable carrier and let them seek contribution. How that works.

What to do

File both claims. Do not choose. Each has its own one-year clock, and choosing wrong is how people end up with neither.

Disclose the prior injury early and completely. It is in the records and it will be found. Disclosed early it is a fact; disclosed late it is a credibility problem, and credibility decides disputed cases. Why that matters.

Get the prior file. The old medical reports, the old rating, and any award. The rating you previously received is the baseline everything gets measured against, and you cannot argue about a baseline you have not read. How to get your file.

And name every body part on both claims. A part left off one claim is a part that gets attributed to the other.

The thing worth knowing

Where a pre-existing disability combines with a new injury to leave you substantially more disabled than either alone, the Subsequent Injuries Benefits Trust FundSIBTF Subsequent Injuries Benefits Trust Fund. Pays where a pre-existing disability plus an industrial injury produce a substantially greater disability. Rewritten by SB 171 in July 2026. can pay the difference. Disability apportioned away from an employer is often precisely what SIBTF exists to address — so an aggressive apportionment defense sometimes points toward a claim nobody has mentioned. How that works.