SIBTF Ratings Before and After Apportionment: Which Number Answers Your Question?

A medical report can show 44 percent before apportionment and 33 percent afterward without the two figures contradicting each other. They may answer different questions: Whether the later injury meets a statutory SIBTF threshold, and what portion of disability is attributable to that injury for the employer’s liability. Label the question before choosing the number.

First identify the governing law. Senate Bill 171 changed California’s SIBTF provisions effective July 13, 2026. Labor Code section 4758 preserves a specified framework for qualifying transition claims. The January 22, 2026 Calderon decision discussed below applied the earlier section 4751 framework. Its numerical lesson must be used with the current transition analysis.

Read the report before doing the arithmetic

Find the doctor’s impairment findings, the rating used for the later injury, and the separate apportionment opinion. Identify whether a figure is whole person impairment, a permanent-disability rating with adjustments, or a rating after allocating causation. A percentage copied from a settlement does not disclose those steps.

In Calderon, decision, page 4–7, Dr. Carr supplied a 44-percent figure before apportionment. Attributing 25 percent to an earlier injury left 75 percent of that figure—33 percent—for the subsequent injury after apportionment. The judge used 33 percent to find the later injury below the 35-percent SIBTF threshold.

The threshold and allocation stages used different numbers

The panel applied Bookout v. Workers’ Comp. Appeals Bd., 62 Cal.App.3d 214, 228 (1976). For the threshold at issue, apportionment was excluded. The correct threshold figure was therefore 44, not 33. The panel found the 35-percent requirement satisfied and returned the remaining issues. Calderon, decision, page 7–9.

The arithmetic is simple: 44 multiplied by 75 percent is 33. The legal task is deciding where that reduction belongs. Applying it too early can change an eligibility answer. Conversely, using the higher figure to state the employer’s final obligation would disregard the separate allocation question. Actual ratings and payment calculations require their own supported findings.

Check the transition facts against section 4758

The current statute lists alternative qualifying events. These include a district-office trial setting before June 1, 2026; a qualifying pretrial conference statement signed and filed before that date; a specified declaration of readiness filed on or before June 1, subject to the readiness and settlement provisions; or an SIBTF application filed on or before July 1, 2020. Read the full applicable alternative rather than reducing the inquiry to “my case is old.”

For the declaration-of-readiness route, the statute distinguishes a matter continued or taken off calendar because it was not trial-ready from one continued or taken off calendar because the parties settled. The docket and minutes can therefore matter as much as the filing date. Bring those documents for review before assuming the preserved rules govern.

Passing one threshold leaves other eligibility questions

The historical framework explained in Todd v. Subsequent Injuries Benefits Trust Fund, 85 Cal.Comp.Cases 576, 581–582 (2020) (en banc), included a qualifying prior disability, a later compensable injury, a greater combined disability and the required combined level. It also contained the alternative opposite-and-corresponding-member route. Calderon, decision, page 6–8, sets out those requirements.

A finding about the 35-percent threshold does not fix the combined rating, available credits, benefit commencement or final amount. Those questions were deferred in Calderon. Prepare the reports addressing each required finding instead of treating 44 percent as a complete SIBTF award.

Prepare a percentage-to-question worksheet

For each number, identify the report and page, what it measures, any age or occupation adjustment, any apportionment reduction and the legal question for which it is offered. Attach the underlying rating and medical explanation. If a report leaves a step unexplained, identify the specific clarification needed rather than supplying a preferred percentage yourself.

Our analysis of Hughes addresses a different problem: Establishing the earlier disability and developing the medical record under a transition provision. This page focuses on the placement of an apportionment reduction in a numerical threshold analysis. Both inquiries need the complete claim history and current law.