The best-kept secret in California comp is a state fund that pays people whose combination of old and new disability crosses 70% — including old conditions that never saw a claim form. Attorneys mine files for it; unrepresented workers almost never find it. And in July 2026 the Legislature rewrote its rules — SB 171 (Stats. 2026, ch. 83, effective July 13, 2026; statutory text per leginfo, checked July 2026) — so most of what the internet says about SIBTF is now out of date.
Why the fund exists
Without it, hiring a worker with one bad eye or an old back would mean insuring the whole history — so nobody would. §4751 splits the bill instead: the employer’s carrier pays for the new injury as if it stood alone; the SIBTF pays the delta between that and the combined disability. Pre-existing means any origin — military service, diabetes, a childhood accident, a prior work injury already settled — but since SB 171 it must have been labor disabling when the new injury happened (§4750): it cost earnings or demonstrably limited work, and a condition that medication or a device kept from limiting work doesn’t count. The scale is why the 2026 rewrite happened: CHSWC’s 2025 annual report puts total fund costs at $446.9 million for FY 2024-25 — up from $34.5 million a decade earlier — with the average paid per claim rising from $13,699 to $80,814 — the full decade of figures in our CHSWC cost brief.
The two doors and the 70% floor — as amended
Door one: the subsequent injury’s whole person impairment, considered alone and after apportionment, is 35% or more. Door two: the prior disability affected a hand, arm, foot, leg, or eye, and the new injury impairs the opposite one at 5% WPI or more — again after apportionment. Through either door, old and new must combine to 70%+ overall. Note what the doors now measure: WPI, the raw impairment number that opens the rating string — not the adjusted percentage that comes out the other end. SB 171 also settles how old and new combine to test the 70%: “combined” now means the PDRS Multiple Disabilities Table or CVC (§4750(b)), and WPI for multiple body parts is combined, not added, at the doors (§4754(b)(3)) — the straight addition of non-overlapping disabilities that once let SIBTF math outrun the CVC (Todd, 2020 en banc) now survives only for claims §4758 keeps under the old rules. Run a file’s numbers against both doors and the floor in the SIBTF calculator.
The July 2026 rewrite: proof is now locked to the file
SB 171’s deeper change is evidentiary (new §4754.1). The preexisting disability must be established by medical records, testimony, and other evidence in existence at the time of the subsequent injury — a retroactive prophylactic work restriction written years later doesn’t count. Medical-legal evidence generally must come from the underlying claim’s evaluation (new evaluations only if none exists or the evaluator is gone), new med-legal cannot relitigate the underlying injury, and vocational reports obtained solely for the SIBTF case are inadmissible and non-reimbursable. Two new bars: an industrial injury that is itself 100% gets no SIBTF on top, and a worker paid a 100%-combined SIBTF award cannot apply again. On the other side of the ledger, the fund must now start paying within 30 days of a final determination of liability. Scope note: §4757 declares these changes procedural and applies them to SIBTF claims without a final determination as of July 13, 2026 — with the new filing deadline expressly carved out of that rule — but §4758 keeps the old rules for claims set for trial, or with a pretrial conference statement filed, before June 1, 2026, most claims with a trial-ready MSC request filed by then, and applications filed by July 1, 2020.
The new hard deadline
New §4754.2: the application must be made within five years of the subsequent injury or six months of the resolution of permanent disability in the underlying claim — C&R, stipulations, or findings and award — whichever is later, and the statute says §3202’s liberal construction cannot extend it. The practical rule: the moment PD resolves, the SIBTF clock is running in months, not years — calendar it with the deadline calculator’s habits, not someday-maybe.
Who this actually helps
Veterans with service-connected conditions plus a work injury are the classic file. Diabetics with neuropathy, workers with prior fusions or amputations, one-eyed workers hurt on the other side — anyone whose new claim carries heavy impairment while their history was already disabling. The thresholds are rating arithmetic: the calculator shows the WPI going into each string and the standalone rating the new injury produces, which is where every SIBTF conversation starts. High-combination cases pay at life-pension-like levels, litigated against the fund at the WCAB alongside the main case.
Statutory framework per leginfo as of July 2026; estimates for informational use; not legal advice — SIBTF practice is specialized, the 2026 rules are new, and counsel is close to mandatory.
Rate your spine right here
Same engine as the tables above — pick your occupation and age, slide the WPI from the report, and carry it into the full calculator when you’re ready.