The Least-Cost-Appropriate-Provider Decision Rule is a standing compliance protocol applied by practitioners in the integrated hybrid SC/PRC model after each direct PRC interaction. The rule operationalises the NDIS Act's requirement that funded supports represent value for money and are the most appropriate and cost-effective option. After every direct PRC service interaction, the practitioner asks a single question: "Could a core-funded support worker have provided this service at a lower cost to the participant's plan?" If the answer is yes, the practitioner reverts to their coordination function and connects the participant to an appropriate core-funded provider. If the answer is no — if the interaction required the practitioner's clinical expertise, relational history, or trauma-informed skills — the PRC billing is justified and continues only for as long as that clinical threshold is met.

The decision rule is structured as a binary test applied at the close of every direct PRC service interaction, before the case note is completed:

Step 1: Characterise the interaction. Was it task-based (transport assistance, appointment accompaniment that required no psychological scaffolding), assistance-based (practical help the participant could access from any trusted worker), or clinical (required the practitioner's relational history, trauma-informed expertise, motivational support, or psychological readiness work)?

Step 2: Apply the test. If the interaction was task-based or assistance-based in nature, the answer is yes — a core support worker at a lower hourly rate could have provided equivalent value. If the interaction was clinical, the answer is no.

Step 3: Document the outcome. The case note records the nature of the interaction, the clinical rationale for direct delivery, and the result of the least-cost test. This creates an auditable trail for each billing decision.

The potential conflict of interest concern in the hybrid model is not the billing category (both SC and PRC draw from the same Category 7 pool at comparable rates) but the volume and intensity of direct PRC hours. A practitioner who uses PRC functions for task-based interactions that a less-expensive core support worker could have performed is not acting in the participant's interest — they are consuming the participant's capacity-building budget inefficiently.

The Least-Cost-Appropriate-Provider Decision Rule is a structural safeguard that makes this distinction explicit, documented, and auditable. It aligns directly with the NDIS Act requirement that supports must be "effective and beneficial for the participant, having regard to current good practice" (s34(1)(e)) and that "the cost of the support is reasonable, relative to both the benefits achieved and the cost of alternative support" (s34(1)(f)).

The decision rule generates a specific documentation trail:

Progress reports to the NDIA distinguish between coordination outcomes and recovery coaching outcomes, demonstrating that genuinely different functions are being performed under each support type rather than identical work being billed under two item codes.

The decision rule operationalises the model's core capacity-building goal: making the practitioner unnecessary for each function as quickly as the participant's recovery allows. As the participant's confidence and self-efficacy build, interactions that previously required clinical scaffolding may become accessible via a core support worker. The practitioner's application of the Least-Cost-Appropriate-Provider rule is the mechanism by which this transition is tracked and implemented at the level of each individual service interaction.