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How this assessment usually works
Multiple injury assessment is not simple addition. NSW guidance requires impairments from the same injury or incident to be handled together, with AMA5 combined-values methodology where relevant. In complex files, a lead assessor may need to coordinate different body-system opinions.
The assessor does not decide legal liability. The assessment is a medical opinion about permanent impairment under the NSW workers compensation guidelines. The legal importance is what the percentage does to Section 66, weekly payments, medical expense time limits, settlement strategy or work injury damages preparation.
Step 1
Accepted injury
Check the accepted injury wording, body system and mechanism before looking at the percentage.
Step 2
Medical method
Check whether the correct NSW guideline method, clinical findings and records were used.
Step 3
Claim effect
Check what the WPI percentage changes before accepting a report or settlement position.
How the assessment pathway is usually built
A useful WPI report should show its working. For multiple injuries and combined impairment, the pathway usually needs these steps before anyone relies on the percentage.
List every accepted injury and body system from the same incident or injury, including any later consequential injury that has been accepted or is being disputed.
Check whether each body system has been assessed under the correct chapter before combining anything.
Use the Combined Values Chart where relevant. Multiple WPI numbers are not simply added together.
Keep primary psychological impairment separate from physical impairment. It cannot be combined with physical WPI.
Consider whether a lead assessor is needed where different specialists assess different body systems.
Assessment method points from the NSW guideline
These points are not a self-calculation tool. They are practical checks for whether the WPI report is using the right body-system method and reasoning.
Multiple impairments from the same injury or incident are generally assessed together and combined using the AMA5 Combined Values Chart where relevant.
The numbers are not simply added. The highest impairment is usually combined with the next highest impairment in the required order.
The assessor should calculate each body-system impairment correctly before combination. A combination chart cannot fix an incorrect source assessment.
Primary psychological impairment is assessed separately from physical impairment and cannot be combined with physical WPI.
Secondary psychological injury receives no separate permanent impairment assessment, although it may still affect treatment, work capacity and damages evidence.
Where different medical assessors are required, a lead assessor may be needed to coordinate and calculate the final WPI.
Impairments from different injuries or dates may have different legal consequences and should not be merged without checking the accepted injury and incident history.
A final combined WPI can affect Section 66, medical expense time limits, weekly payment strategy and work injury damages threshold advice.
What can change the WPI percentage
The final percentage can move because of method selection, objective findings, surgery, pre-existing deduction, or how multiple impairments are combined. These are the practical pressure points for this injury type.
- Whether all accepted injuries and body systems have been included.
- The order of combination, usually starting with the highest impairment and combining the next highest in turn.
- Whether deductions for pre-existing conditions have been made before or after the correct body-system assessment.
- Whether the final report explains each source number and the combined final WPI.
- Whether primary psychiatric impairment, secondary psychological symptoms and physical impairment have been separated correctly.
What the assessor usually checks
- which injuries arose from the same incident or compensable injury
- whether separate body systems need separate specialists
- whether primary psychological impairment is kept separate from physical impairment
- whether combined-values reasoning is explained rather than guessed
- whether the final WPI percentage is linked to Section 66, weekly payments and work injury damages consequences
Evidence that may help
A useful WPI report depends on the material the assessor receives. These records often matter for multiple injuries and combined impairment:
- all specialist reports and the material sent to each assessor
- accepted injury descriptions and insurer notices
- lead assessor report or coordination material where multiple body systems are involved
- operation notes, imaging, psychological reports and capacity evidence
- a chronology showing how each injury affects work and daily function
Common insurer or report disputes
- percentages are treated as if they can simply be added together
- one injury is omitted from the final impairment calculation
- physical and primary psychological impairments are incorrectly combined
- different assessors rely on different histories
- the insurer relies on the final number without explaining the pathway
Report cautions before relying on the percentage
Report red flags
- The final WPI is calculated by simple addition rather than the Combined Values Chart.
- A body system is missing because it was not sent to the right specialist.
- Primary psychiatric and physical impairment are combined into one total.
- The report gives a final number without showing the source ratings, deductions and combination steps.
Method and reliance checks
- Are all accepted injuries and body systems included?
- Do different assessors rely on a consistent injury history and documents?
- Is a lead assessor needed to coordinate the final WPI?
- Does the final report explain combination, deductions and threshold consequences?
- Have primary psychiatric impairment and physical impairment been kept separate?
- Were any consequential injuries or disputed body systems excluded, and if so is the reason clear?
- A missing body-system report can understate the final WPI.
- Incorrectly combining physical and primary psychological impairment can create a legally unreliable number.
- The final percentage should be reviewed before it is used for Section 66, weekly payments or work injury damages threshold advice.
Guideline notes
- The NSW guideline uses the AMA5 Combined Values Chart for multiple impairments where relevant.
- Psychological and physical impairment have special separation rules.
Questions to ask when the report comes back
How this connects to thresholds and strategy
SIRA says permanent impairment compensation generally requires 11% or more permanent impairment for physical injury, and 15% or more for primary psychological injury. Secondary psychological injury is treated differently. Those thresholds are not a payout promise; they are eligibility and strategy checkpoints that need to be applied to the accepted injury and current evidence.
A low WPI opinion may also affect weekly-payment planning, treatment time-limit issues, dispute posture, and whether work injury damages threshold advice is required. The safest approach is to review the method, evidence and consequences before signing or letting the insurer rely on a weak assessment.
Questions workers often ask
Is multiple injuries and combined wpi assessed the same way as every other injury?
No. NSW permanent impairment assessment depends on the accepted injury, body system, medical evidence, maximum medical improvement and any NSW-specific guideline modification. The assessment method for multiple injuries and combined wpi should be checked against the injury actually accepted in the claim.
Can I calculate the WPI percentage myself?
No. A trained permanent impairment assessor must perform the assessment. A worker can still check whether the report used the correct injury description, records, body system, causation assumptions and deduction reasoning.
What if the insurer report seems too low?
Ask for the report and the material sent to the assessor. For multiple injuries and combined wpi, compare the report against treating records, imaging, specialist material, work duties and certificates of capacity before accepting the percentage or relying on it for settlement strategy.
Does maximum medical improvement matter?
Yes. SIRA guidance says permanent impairment assessment should occur when the condition has stabilised and is unlikely to change substantially in the next year with or without treatment. If treatment is incomplete, the timing may need review.
General information only
This information is general in nature and is not legal advice. You should obtain advice about your own circumstances before relying on a WPI percentage, accepting a lump sum offer, or responding to an insurer decision.
Reviewed by NSW Work Injury Claims - a branch of Stephen Young Lawyers.
Related injury and impairment pages
Need a WPI assessment checked?
If the percentage does not match the accepted injury, treatment history, imaging, surgery, work duties or current restrictions, get the report checked before accepting the insurer position.