What is a whole person impairment (WPI) assessment and why does the threshold matter?

Whole person impairment, or WPI, is the number that unlocks the larger claims. It is a percentage that expresses how much a permanent injury has reduced your whole body's function, assessed by a trained doctor against a published guide. In several Australian schemes the percentage decides whether you can claim a lump sum at all, so the assessment is one of the most important events in a claim.

The short answer

WPI is a medical rating, from 0% to 100%, of permanent loss of function caused by the injury. It is assessed once the injury has stabilised, by a doctor accredited under the scheme, using the scheme's impairment guidelines. Thresholds then turn the number into entitlements: at least 15% for a NSW work injury damages claim for a physical injury, at least 15% for a WA common law claim, 30% for serious injury benefits in South Australia, and more than 5% or 10% for a Victorian significant injury.

How the assessment works

The assessor examines you, reviews your records and imaging, and rates each injured body part or system against the guide the scheme adopts. Ratings for different injuries are combined, not added, so two 10% ratings do not make 20%. Physical and psychological injuries are assessed separately and, in NSW, are not combined for threshold purposes (Workers Compensation Act 1987 s 151H).

Three rules shape the outcome:

• Stabilisation. The injury must have reached maximum medical improvement. Assess too early and the rating is provisional or low.
• Pre-existing conditions. The assessor deducts impairment that existed before the injury. Honest disclosure matters; a hidden history discovered later damages the whole claim.
• The guide, not the pain. WPI rates loss of function, range of motion and objective findings. Pain that does not show in function rates low, which is why consistent clinical records matter.

The thresholds by scheme

Scheme	What WPI unlocks	Threshold	Source
NSW workers compensation	Work injury damages (negligence claim against the employer)	At least 15% physical, at least 25% psychological	Workers Compensation Act 1987 s 151H
WA workers compensation	Common law damages against the employer	At least 15% permanent whole of person impairment	WorkCover WA
SA Return to Work scheme	Serious injury benefits	30% or more (35% for physical injuries under the serious injury package)	ReturnToWorkSA
Victoria negligence claims (Wrongs Act)	Non-economic loss	Significant injury: more than 5% physical, 5% or more spinal, 10% or more psychiatric	Justice Victoria
SA CTP claims	Future economic loss	Injury scale value of 8 or more (a related but different scale)	CTP Insurance Regulator
Queensland negligence claims	General damages	Injury scale value from 0 to 100 (not WPI, but assessed from impairment)	Civil Liability Act 2003

New South Wales negligence claims outside the workers compensation and CTP schemes use a different test for non-economic loss: severity of at least 15% of a most extreme case (Civil Liability Act 2002 s 16). It is a judicial assessment rather than a medical percentage, but the same medical evidence feeds it.

Why one percentage point matters

A rating of 14% and a rating of 15% can be the difference between a permanent impairment lump sum alone and a damages claim for lost earnings to retirement. Insurers know this, and disputes cluster around the threshold. In workers compensation schemes a disputed assessment is usually referred to an independent medical assessor appointed by the tribunal or regulator, whose rating binds the parties. Preparation is therefore not about persuading the assessor; it is about making sure the assessor sees the full, accurate picture.

What happens at the assessment

The appointment usually lasts an hour or more. The assessor takes a history of the injury, the treatment and your current symptoms, reviews the records you and the parties have provided, and examines you. For a back or neck injury that means measuring range of motion, testing strength, reflexes and sensation, and observing how you move. For a brain injury it may include cognitive testing or a review of neuropsychological reports. For a psychological injury the assessment is an interview against a set of functional scales.

The rating is then calculated under the guide the scheme adopts. Most Australian schemes base their guidelines on editions of the American Medical Association guides, modified for local use, which is why two assessors following the same guide should reach similar figures for the same findings. Where they do not, the difference usually lies in the history taken, the interpretation of imaging or the deduction for pre-existing conditions, and those are the points to raise if you dispute the result.

You are entitled to a written report. Read it for factual errors, such as the wrong date of injury, a missed operation or a misdescribed job, and raise them promptly through your lawyer. A factual error is easier to correct than an opinion is to challenge.

After the assessment

If the rating meets the threshold, the next step is the lump sum or the damages claim. If it falls short, the options depend on the scheme: some allow a further assessment after deterioration, some allow a dispute before an independent panel, and in a negligence claim the assessment is evidence rather than a binding decision. Do not accept an offer based on a rating you believe is wrong without advice, because in most schemes a permanent impairment lump sum can be claimed only once.

How to prepare

1. Wait for stabilisation. Ask your treating specialist whether you have reached maximum medical improvement.
2. Gather the records. Imaging reports, operation notes, specialist letters and physiotherapy notes.
3. Write a function list. What you could do before, what you cannot do now, and what you do differently. Sitting and standing tolerance, lifting, driving, sleep, dressing, work tasks.
4. Disclose the history. Earlier injuries and conditions, with dates.
5. Bring a support person if you need help remembering or communicating.
6. Get advice on timing if a limitation period for a damages claim is approaching, generally 3 years from discoverability in NSW (Limitation Act 1969 s 50C).

Frequently asked questions

Who chooses the assessor? In most schemes each side can obtain an assessment, and a disputed rating is referred to an independent assessor whose decision binds. Ask your lawyer how it works in your state.

Can my WPI be reassessed? Usually only if the injury has deteriorated and the scheme allows a further assessment. Timing the first assessment well is better than relying on a second.

Does WPI decide how much money I get? It decides the permanent impairment lump sum directly and whether the larger damages claims are open. The damages themselves are assessed on lost earnings and the other heads of damage.

Is pain included? Only as it affects function and objective findings under the guide. Keep clinical records that describe what you cannot do, not only how it feels.

This article is general information, not legal advice, checked on 26 September 2026. The guides adopted by each scheme and the thresholds can change. An enquiry with Australian Claim Helpline does not lodge a claim or pause a time limit; the personal injury lawyers guide explains each pathway.

General information published 26 September 2026. It is not legal advice and may not reflect later changes to the law or a scheme. Check your own position with a qualified adviser.

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