"I've had a claim before."

What actually reduces your case

§ 4664(b): where there has been a prior award of permanent disability, that disability is conclusively presumed to still exist.

Note what that requires: a prior award. A prior claim that resolved by Compromise and Release without an award of permanent disability is not a prior award — and § 4664(b) gets asserted more often than it applies. Ask to see the prior award.

And § 4663 apportionment is to the causation of disability. Be careful with Lindh*: under City of Petaluma v. WCAB (Lindh) (2018) 29 Cal.App.5th 1175, a pre-existing condition that never disabled you *can support apportionment — prior disability is no longer a prerequisite. What the defense must still prove is that the condition actually caused part of this disability, on substantial medical evidence.

Under Escobedo, the opinion must explain how and why. A percentage attached to "prior injury" without reasoning is not substantial evidence. How to attack an apportionment opinion.

What may increase it — SIBTF

The Subsequent Injuries Benefits Trust Fund exists for workers who had a pre-existing disability and then suffered an industrial injury that, combined, produces a substantially greater disability.

It is paid by a state fund, not by your employer — which means it is genuinely additional money, and it is chronically under-claimed.

And it changed. SB 171 rewrote SIBTF effective July 2026, retroactively, with a June 1, 2026 grandfather snapshot.

Every SIBTF page in California written before that is now describing a system that no longer exists. What changed and what it means.

A prior disability that qualifies does not have to be industrial. A congenital condition, a prior non-work injury, or a medical condition can be the pre-existing disability.

Which is why honesty at the deposition matters

You will be asked about prior injuries and prior claims under oath. More on testifying.

Answer honestly. A prior injury does not defeat your claim, and it may be worth money. What does destroy a claim is denying something that appears in a medical record somewhere — and it always appears in a medical record somewhere.