Two small houses of the same height side by side on one plinth, one built from standard components with plans, the other with a custom facade beside test samples and a laptop graph.

What is the difference between DTS and Performance Solutions under the NCC?

In short

  • The NCC’s Performance Requirements are the only technical provisions you must meet. You meet them with a Deemed-to-Satisfy (DTS) Solution, a Performance Solution, or a combination of the two (A2G1).
  • A DTS Solution follows the prescriptive provisions and is deemed to comply. A Performance Solution shows compliance through one or more of four Assessment Methods, backed by evidence and a documented process (A2G2).
  • NCC 2025 removes Expert Judgement as an Assessment Method for a listed set of structural and fire safety Performance Requirements. It remains available elsewhere.
  • For Performance Solutions using listed structural materials, NCC 2025 also requires the solution to be at least equivalent to the DTS Provisions (A2G2(5)). That starts one year after your state adopts NCC 2025.
  • NSW and Victoria have their own versions of A2G2, and several states are still on NCC 2022. Check which edition and which version applies before you rely on either rule.

Correct as at September 2026.

Every compliance conversation with a certifier eventually comes back to one question: are you following the recipe, or proving your own? Get the answer clear early and approvals move. Leave it vague and you find out at the worst possible stage.

Here is how the two pathways work, what NCC 2025 changes, and where the changes do and do not apply yet.

How NCC compliance is structured

The NCC is a performance-based code. Under A2G1, you comply by meeting the Governing Requirements and the Performance Requirements. The ABCB’s explanatory information puts it plainly: the Performance Requirements are the only NCC technical provisions that must be satisfied.

A2G1(2) gives three ways to satisfy them: a Performance Solution, a Deemed-to-Satisfy Solution, or a combination of both. The same structure sits in Part A2 of Volumes One, Two and Three.

Deemed-to-Satisfy: the recipe

A DTS Solution follows the relevant DTS Provisions. The ABCB describes them as prescriptive, “like a recipe book”: they set out the materials, components, design factors and construction methods that are deemed to meet the Performance Requirements.

Under A2G3, a DTS Solution can show it complies with the DTS Provisions through Evidence of Suitability under Part A5, Expert Judgement, or both.

The advantage is certainty. You document to the clauses, the certifier checks against the same clauses, and the argument is short. The cost is rigidity. DTS Provisions were not written for every building, and some Performance Requirements have no DTS Provisions at all, so a Performance Solution is the only route.

Performance Solutions and the four Assessment Methods

Under A2G2(1), a Performance Solution is achieved by showing it complies with all relevant Performance Requirements, or that it is at least equivalent to the DTS Provisions. Under A2G2(2), you show that through one or a combination of four Assessment Methods:

  1. Evidence of Suitability under Part A5.
  2. A Verification Method, either one in the NCC or another accepted by the appropriate authority.
  3. Expert Judgement.
  4. Comparison with the DTS Provisions.

A2G2(3) tells you how to find the relevant Performance Requirements: those in the Section or Part the solution applies to, plus any in other Sections or Parts the solution affects.

A2G2(4) then sets the process. Prepare a performance-based design brief with the relevant stakeholders, carry out the analysis it proposes, and evaluate the results against its acceptance criteria. The final report must list the Performance Requirements and DTS Provisions identified, the Assessment Methods used, the steps taken, confirmation that the Performance Requirement is met, and any conditions or limitations on the solution.

Combining the two

A2G4 lets you use Performance Solutions and DTS Solutions together, and many complex buildings do: a fire-engineered egress solution alongside DTS everything else is common. Under A2G4(3), you identify the DTS Provisions the Performance Solution replaces, the Performance Requirements in the same Section or Part that relate to them, and any Performance Requirements elsewhere that the solution affects. The A2G2(4) process still applies to the Performance Solution part.

What NCC 2025 changes

The ABCB describes the NCC 2025 changes as affecting structural reliability and fire safety Performance Solutions. There are three parts.

Expert Judgement is limited. A new Limitation under A2G2 says Expert Judgement (A2G2(2)(c)) does not apply to demonstrating compliance with these Performance Requirements, to the extent they relate to structural or fire safety:

  • Volume One: B1P1(2); C1P1 to C1P9; D1P1 to D1P10; E1P1 to E1P6; E2P1 and E2P2; E3P1 to E3P4; and E4P1 to E4P3.
  • Volume Two: H1P1(2).

DTS equivalence for listed structural materials. New subclause A2G2(5) says that where compliance with B1P1(2) or H1P1(2) is proposed through a Performance Solution for materials in B1D4(a) to (f), or clauses 2.2.4(d) and 2.2.4(g) to (k) of the Housing Provisions, the solution must be shown to be at least equivalent to the DTS Provisions. The ABCB lists those materials as including masonry, concrete, steel, composite steel and concrete, aluminium and timber.

A structural Verification Method. The ABCB says NCC 2025 introduces a new Verification Method for structural reliability Performance Solutions (B1V1), and practitioners developing those solutions must use it.

What has not changed. Expert Judgement remains available for Performance Solutions in other parts of the NCC. And the ABCB is clear that removing it as an Assessment Method does not stop you applying professional judgement within the other methods.

When and where the changes apply

NCC 2025 took effect in Victoria on 1 May 2026, is optional alongside NCC 2022 in the ACT and WA until 1 May 2027, and is due in NSW, Queensland, SA and Tasmania on 1 May 2027. The NT has not adopted it. For the detail, read NCC 2025 vs NCC 2022: what changed, and when it applies in your state.

A2G2(5) carries its own one-year delay: it does not take effect until one year after NCC 2025 is adopted in your state. On current adoption dates, that is 1 May 2027 for Victoria, the ACT and WA, and 1 May 2028 for Queensland, SA and Tasmania if their 1 May 2027 adoption holds. The Expert Judgement limitation has no delay, so it applies from the day NCC 2025 applies to your project.

Two states have replaced A2G2 with their own version, so read the variation before you rely on the national text:

  • Victoria. The Victorian A2G2 keeps Expert Judgement as an Assessment Method and does not carry the national Expert Judgement limitation list. It keeps Victoria’s existing ban on using a Performance Solution for combustible cladding on certain buildings. For the listed structural materials, the solution must be shown to be at least equivalent to the DTS Provisions and assessed by Comparison with the DTS Provisions, from one year after adoption.
  • NSW. As published on NCC online, the NSW version of A2G2 for NCC 2025 includes neither A2G2(5) nor the Expert Judgement limitation. NSW moves to NCC 2025 on 1 May 2027, so check again before then.

Who does what

The designer chooses the compliance pathway and documents it. Performance Solutions usually involve a specialist, such as a fire engineer, structural engineer or building physicist, depending on the Performance Requirement. The builder builds to the documents. The building surveyor or certifier has to be satisfied that the documents show compliance and that the building matches them. They review a Performance Solution; they do not write it.

When something is challenged later, the paperwork is the defence. A Performance Solution without a proper design brief and final report under A2G2(4) is a common reason approvals stall.

Three common misconceptions

  • “A Performance Solution is a shortcut.” It means more documentation, not less. Without evidence under an accepted Assessment Method, it is a compliance failure.
  • “A Performance Solution lowers the bar.” Both pathways must meet the same Performance Requirements. They differ in method, not outcome.
  • “Expert Judgement is gone.” Under NCC 2025 it is gone only for the listed structural and fire safety Performance Requirements, and Victoria has kept it more broadly. It is still an Assessment Method everywhere else.

CPD on NCC compliance pathways

These live courses run one hour each and cover the NCC’s structure, compliance pathways and the evidence behind them:

To see how these fit your annual obligations, read the CPD requirements guide and the CPD deadlines calendar.

Frequently asked questions

What is the difference between a DTS Solution and a Performance Solution?

A Deemed-to-Satisfy Solution follows the NCC’s prescriptive provisions and is deemed to meet the Performance Requirements. A Performance Solution meets the Performance Requirements another way, shown through one or more Assessment Methods and documented through the process in A2G2(4). Both must meet the same Performance Requirements.

What are the four Assessment Methods for a Performance Solution?

Under A2G2(2) they are Evidence of Suitability under Part A5, a Verification Method, Expert Judgement, and Comparison with the Deemed-to-Satisfy Provisions. You can use one or a combination.

Has NCC 2025 removed Expert Judgement?

Only in part. Under the national NCC 2025 text, Expert Judgement cannot be used to show compliance with listed structural and fire safety Performance Requirements in Volume One and with H1P1(2) in Volume Two, to the extent they relate to structural or fire safety. It remains available for other Performance Requirements. Victoria’s variation keeps it more broadly.

When does the NCC 2025 structural equivalence rule start?

A2G2(5) takes effect one year after NCC 2025 is adopted in your state. On current adoption dates that is 1 May 2027 in Victoria, the ACT and WA, and 1 May 2028 in Queensland, SA and Tasmania if their 1 May 2027 adoption holds.

Can I combine DTS and Performance Solutions on one project?

Yes. A2G4 allows a combination. You must identify the DTS Provisions the Performance Solution replaces, the related Performance Requirements, and any other Performance Requirements the solution affects, and follow the A2G2(4) process for the Performance Solution.

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