Answer first: Since 31 July 2026, you no longer upload a BASIX certificate to a DA or CDC on the NSW Planning Portal. You type the certificate reference number into the application form, and the Portal validates it before you can submit. Expired, duplicated or invalid numbers block lodgement; an address mismatch flags the certificate “Review required” for council or the certifier.
By: giantA Pty Ltd · Updated 8 October 2026
What changed for BASIX certificates on the NSW Planning Portal in 2026?
Uploading the BASIX certificate PDF with your plans is no longer part of lodgement. According to the Department of Planning, Housing and Infrastructure’s BASIX validation messages information sheet (31 July 2026), the 31 July release strengthened compliance and security for BASIX certificates by making two changes:
- applicants no longer manually upload a BASIX certificate; and
- applicants enter the certificate reference number in the application form, and it is validated — based on the local government area and postcode — before the application can be submitted.
The BASIX Newsletter August 2026 gives an example of the format (1234567M) and confirms the change applies to new and “In progress” applications. If you started a DA or CDC before the change but have not submitted it, go back in and enter the reference number first.
Two follow-up releases refined the system. The 28 August 2026 release summary tightened the validation messages, stopped edited applications progressing until validation is complete, prevented edits to already-validated certificates, and hid unreviewed superseded certificates from applicants. On 7 September 2026, the Department’s BASIX certificate improvements notice added clearer status messages for councils and certifiers, and better instructions for applications that were mid-way through the transition.
In practice, errors that once surfaced as a council request for information now stop the application at the submit button.
Which applications does BASIX certificate validation apply to?
The information sheet lists the impacted services as the complying development certificate service and the development application (Council and State) services. The Department’s step-by-step guide for councils and certifiers, How to validate a BASIX certificate marked as ‘Review required’ (version 2, 28 August 2026), says the same: from 31 July 2026, reference numbers entered in DA, State significant development (State DA) and CDC applications are automatically validated against the records held in the BASIX service.
That covers new houses, granny flats, dual occupancies, apartments, and alterations and additions that need a certificate. The published guidance does not describe the same automated check for construction certificate applications, so do not assume it — the certificate still has work to do at construction and occupation stage.
What do the BASIX validation messages mean, and what should you do?
When you enter a reference number, the Portal returns one of five messages. The table below summarises the information sheet; the wording on screen may differ slightly.
| Message type | What the Portal is telling you | Can you submit? | What to do |
|---|---|---|---|
| Success | The certificate has been validated | Yes | Nothing. The certificate appears on the application’s ‘Documents’ tab for the applicant, council and certifier. |
| Error — already entered | The same reference number is in the form twice | No | Delete the duplicate using the recycle bin icon next to it. |
| Error — more than 3 months old | The certificate was generated more than three months ago | No | Delete it and enter a certificate generated in the last three months. This may mean revising the certificate in the BASIX service. |
| Error — not valid | The number does not match a valid certificate | No | Delete it and enter a valid reference number. Check for typing errors first. |
| Warning — address mismatch | The certificate address does not match the application address | Yes, but flagged | Check the certificate belongs to the right property. If it does, the council or certifier reviews it during assessment. You cannot view it in the application until it is released. |
The three-month error is not new policy. The Portal’s certificate validity page has long said a certificate is valid for three months before submission and, once lodged, for the life of the development application. What has changed is enforcement: the Portal now checks the generation date itself. For more on the validity clock, see our guide to BASIX certificate validity and the 3-month lodgement window.
Why would a BASIX certificate be marked ‘Review required’?
A “Review required” tag means the Portal found the certificate, but the address on it does not match the address in your application. According to the Department’s guide, the certificate is still uploaded to the ‘Documents’ tab, but while the tag remains the applicant cannot view or download it from that tab. The certificate is still available in the BASIX service where it was generated.
There is a second, less obvious trigger. The information sheet notes that if you use the manual address functionality when creating an application, any BASIX reference numbers you enter will be marked for review by the council or certifier.
In our experience, mismatches usually come from ordinary project realities: a corner site with two street frontages, a lot that has been subdivided or consolidated since the certificate was generated, a new subdivision without allocated street numbers, or a granny flat entered with a different address in the BASIX tool. None makes the certificate wrong, but each adds a manual step for the consent authority. Use the same property details in the BASIX tool and the DA or CDC form so the check passes first time.
What does the council or certifier do with a ‘Review required’ certificate?
The Department’s guide sets out the process for council officers and certifiers, who need a council or certifier account on the Planning Portal:
- Open the application from the relevant workbasket and select ‘Review BASIX certificates’ from the ‘Actions’ menu.
- If the certificate is valid, untick the review box and submit. The tag is removed, the status updates to “reviewed and validated”, and the applicant can see the certificate.
- If it is not valid, leave the box ticked and use ‘Edit application’ to delete that reference number.
The guide sets no timeframe for this review, so resolve a likely mismatch before lodgement rather than relying on it being cleared quickly.
How do you avoid BASIX validation errors before lodging a DA or CDC?
Most validation problems are preventable in the last week of design. This is the sequence we run before a reference number goes into a Portal form:
- Confirm BASIX applies and which pathway. New dwellings, alterations and additions with an estimated development cost of $50,000 or more, and pools or spas of 40,000 litres or more all need a certificate. The Starting a BASIX application page maps each project type to the single dwelling, multi-dwelling or alterations and additions pathway — and once you start the application, the pathway cannot be changed.
- Stay on the BASIX report until the design is frozen. The Portal’s validity guidance recommends using the report function until the design is finalised and ready for lodgement, to avoid extra fees for a new certificate. Generating the certificate too early is the usual route to the three-month error.
- Use the same property address everywhere. Match the BASIX project address to the property you will select in the DA or CDC form, and avoid the manual address option unless the property genuinely cannot be found.
- Check units on pools and spas. The August 2026 newsletter reminds users that the BASIX tool calculates in kilolitres, so a pool or spa volume must be entered in kL, not litres (1 kL = 1,000 L).
- Confirm the accuracy declaration. Since the 1 May 2026 BASIX release, you must tick a compulsory box confirming the information — including any NatHERS assessor information — is true and correct before the certificate can be generated. False or incorrect information breaches the BASIX Terms and Conditions and may lead to compliance action.
- Put every commitment on the plans. The Portal states that the commitments on the certificate must be noted on the plans. Glazing, insulation, hot water, lighting, fixtures, rainwater tanks and pool equipment should all be traceable from certificate to drawing.
- Enter each reference number once, then submit inside three months. Diary the generation date against your lodgement date, and check the Success message appears for every certificate before you submit.
If the project uses the Simulation method, the thermal performance inputs come from NatHERS-accredited software, which the Portal’s thermal performance guidance describes as a more detailed assessment suited to complex designs and multi-dwelling projects. Coordinate the assessor’s final run with the architectural set so the certificate, NatHERS stamped plans and DA drawings describe the same building.
What if the design changes after the certificate has been validated?
Design changes still need a revised BASIX certificate. The Portal’s BASIX and planning approvals page says that if you change your project you must revise the BASIX certificate and resubmit it to council, and that there is no charge to revise a valid certificate lodged with the consent authority. The validity page adds that a free revision must relate to the same property and project as the original certificate.
What 2026 adds is tighter control of the entry itself: validated certificates cannot be edited, and an edited application cannot progress until validation is complete. Our practical reading: treat a revised certificate as a fresh entry that must pass validation in its own right, and ask the assessing officer or certifier how they want the superseded certificate handled.
Typical triggers are changes to floor area, glazing, insulation, hot water or heating and cooling systems, fixtures, tank size, or pool volume. If a commitment no longer matches the drawings, revise it before amended plans go in.
Can you enter more than one BASIX certificate on an application?
The form supports it through an ‘Add another BASIX certificate’ option. Whether you should is a separate question.
The Portal’s guidance on when more than one BASIX certificate should be submitted says that for new dwellings, the development application must include one BASIX certificate covering all dwellings. The consent authority, usually the local council, may allow a project to be split across separate certificates, but the applicant must ask for that approval. The guidance gives four examples where a split may be sought:
- Torrens title subdivision with detached houses and no common property or shared services;
- strata developments where common areas and shared services can be apportioned;
- staged development; and
- large multi-tower residential flat developments of more than 600 units.
The duplicate error only catches the same number entered twice; it will not tell you whether council has agreed to separate certificates. Get that agreement first. For dual occupancies, see our guide to the BASIX multi-dwelling pathway for dual occupancy.
What happens to the BASIX certificate after DA or CDC approval?
Validation at lodgement is only the first check. The Portal’s BASIX and planning approvals page describes the rest of the path:
- Assessment: if approved, the development must be built according to the BASIX commitments.
- Construction certificate: attach the BASIX certificate to the construction certificate application and make sure all commitments are shown on the plans. The certifying authority inspects construction.
- Occupation certificate: attach the BASIX certificate to the occupation certificate application. After the final inspection and before the occupation certificate is issued, the certifying authority must issue a BASIX completion receipt confirming the project was built as per the certificate.
The Portal’s council or certifier page confirms councils check BASIX certificate information when assessing DAs and CDCs, and certifiers check it before issuing a construction or occupation certificate. A clean validation at lodgement will not help if the windows, insulation or hot water system on site differ from the certificate.
How does validation work for alterations and additions over $50,000?
The same way. BASIX applies to all alterations and additions in NSW valued at $50,000 or more, and to pools and spas with a total volume greater than 40,000 litres, according to the Portal’s alterations and additions page. If the renovation is lodged as a DA or CDC through the Portal, its BASIX reference number goes through the same validation as a new house.
Two points catch renovators out. First, the Department’s December 2025 BASIX newsletter confirms a certificate is required for every alteration or addition of $50,000 or more, regardless of the nature of the work — even when the certificate ends up with no commitments, such as for some verandahs, covered outdoor areas or brickwork repairs. Second, a new granny flat, or a garage converted into a new dwelling, is assessed as a new single dwelling, not as alterations and additions. Choose the wrong pathway and you will need a new certificate.
Our earlier guides cover the renovation side in more depth: when your renovation triggers a BASIX certificate, why you still need a certificate over $50k with no commitments, the 40,000-litre pool and spa trigger, and the May 2026 BASIX tool upgrades for alterations glazing.
Where does giantA fit in?
BASIX validation rewards a tidy handover between design and lodgement: frozen drawings, a certificate generated at the right moment, consistent property details and commitments visible on every sheet. Our BASIX and NatHERS service covers assessments, certificates, NatHERS coordination and plan mark-ups from our Parramatta studio. For Sydney projects, see BASIX assessment in Sydney. If you are still deciding between exempt development, a CDC or a DA, start with our approval pathway guide, or see our step-by-step guide to getting a BASIX certificate. For a project-specific answer, contact giantA or browse our services.
Frequently asked questions
Do I still upload my BASIX certificate PDF with a DA or CDC?
No. Since 31 July 2026, you enter the BASIX certificate reference number in the Planning Portal application form instead of uploading the certificate. The number is validated before you can submit, and a validated certificate appears automatically on the application’s ‘Documents’ tab.
Why does the Portal say my BASIX certificate is more than 3 months old?
A BASIX certificate is valid for three months before it is lodged. If it was generated earlier than that, the Portal will not accept it. Delete the entry and enter a certificate generated in the last three months, which may mean revising it in the BASIX service.
Can I still submit if my certificate is marked ‘Review required’?
Yes. An address mismatch is a warning, not an error. The council or certifier reviews the certificate during assessment. If it is valid they release it; if not, they remove the reference number from the application and you will need to supply a correct certificate.
Does using the manual address option affect BASIX validation?
Yes. The Department’s information sheet says that if you create an application using the manual address functionality, any BASIX reference numbers you enter will be marked for review by the council or certifier.
Does the $50,000 alterations threshold still apply?
Yes. BASIX applies to alterations and additions valued at $50,000 or more, and to pools and spas of 40,000 litres or more. A renovation DA or CDC with a BASIX certificate goes through the same reference number validation as a new home.
Do I need a new BASIX certificate if I change the design after lodgement?
Yes, if the change affects anything on the certificate. The Portal says there is no charge to revise a valid certificate lodged with the consent authority for the same property and project. Enter the revised certificate so it passes validation, and update the plans to match.
Preferred sources (verify current versions)
- NSW Planning Portal — Information sheet: BASIX validation messages (31 July 2026, PDF)
- NSW Planning Portal — How to validate a BASIX certificate marked as ‘Review required’ (v2, 28 August 2026, PDF)
- NSW Planning Portal — BASIX Newsletter August 2026
- NSW Planning Portal — BASIX certificate improvements in the NSW Planning Portal (7 September 2026)
- NSW Planning Portal — 28 August 2026 release summary
- NSW Planning Portal — 1 May 2026 release summary
- NSW Planning Portal — Validity of the certificate and changes to the project
- NSW Planning Portal — BASIX and planning approvals
- NSW Planning Portal — Starting a BASIX application
- NSW Planning Portal — When should more than one BASIX certificate be submitted?
- NSW Planning Portal — BASIX alterations and additions
- NSW Planning Portal — BASIX: Council or Certifier
- NSW Planning Portal — BASIX Newsletter December 2025
- NSW Planning Portal — BASIX thermal performance section