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Yes! You can use AI to fill out Building Regulation 2021 (Queensland) – Section 143A(3) – Form 18 (Version 6, March 2023), Notice to the owner (where owner is not the client) that a private certifier has been engaged

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Building Regulation 2021 (Queensland) – Section 143A(3) – Form 18 (Version 6, March 2023), Notice to the owner (where owner is not the client) that a private certifier has been engaged, page 1

Basic · 45/100Form Complexity Index

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What this form asks for

The AI fills all of it, from your answers or your documents.

Form 18 is the approved Queensland form required under section 143A(3) of the Building Act 1975 when a private certifier is engaged by a client who is not the building owner. It formally provides the owner with the certifier’s identity, engagement date, inspection scope/fee coverage, property details, and the proposed building work description, helping ensure transparency and compliance with statutory notice requirements (generally within 15 business days of engagement). It also supports the owner’s rights to request inspection documentation or additional certifying functions (via related forms such as Form 35 and Form 31). Today, this form can be filled out quickly and accurately using AI-powered services like Instafill.ai, which can also convert non-fillable PDF versions into interactive fillable forms.

Fillable fields41

Pages2

Sections10

Questions that depend on earlier answers5

Form Complexity IndexBasic, 45/100

The AI checks your answers before you download

16 checks built for this form, so a wrong date or a missing answer is caught before anyone else sees it.

Owner Notification Checkbox Must Be Affirmatively Selected

Validates that the checkbox indicating the form is being used to notify the owner (who is not the client) is checked. This is important because Form 18 is only applicable when the owner is not the client and the notice is being sent to the owner. If not selected, the submission should be rejected or flagged as an incorrect form/use-case and require user confirmation before acceptance.

Private Certifier Identity Completeness (Name + Licence Number Required)

Ensures the private certifier’s full name and licence number are both provided and not placeholders (e.g., 'N/A', 'TBA'). This is critical for legal traceability and for verifying the certifier is authorised to perform certifying functions. If either field is missing or invalid, the form should fail validation and prompt for correction.

QBCC/Certifier Licence Number Format Validation

Checks that the licence number matches the expected format rules (e.g., numeric length/structure as configured for the issuing authority) and contains only permitted characters. This reduces data entry errors and supports downstream verification against licensing registers. If the format check fails, block submission and require a corrected licence number.

Engagement Date Format and Valid Calendar Date

Validates that the Date of engagement is provided in DD/MM/YYYY format and represents a real calendar date (e.g., not 31/02/2025). This is important because statutory timeframes in the form are based on the engagement start date. If invalid or missing, the submission should be rejected and the user prompted to enter a valid date.

Signature Date Format and Not Earlier Than Engagement Date

Ensures the private certifier signature date is in DD/MM/YYYY format, is a valid date, and is not earlier than the engagement date. This prevents logically impossible timelines (signing before engagement) and supports audit defensibility. If the signature date is invalid or precedes engagement, fail validation and require correction.

Statutory Timing Check: Notice Sent Within 15 Business Days of Engagement

If the system captures a submission/sent date, validate that the notice is being issued within 15 business days after the engagement starts (as stated in the form text). This check is important for compliance monitoring and to flag late notices that may require a 'reasonable excuse' workflow. If outside the window, the system should warn/block and require an override reason or compliance flag.

And 10 more checks

Property Address Completeness and Postcode Format
State/Territory Must Be One of Allowed Values and Consistent Across Addresses
Lot and Plan Details Presence and Pattern Validation
Local Government Area (LGA) Required and Non-Placeholder
Owner Details Completeness and Company Contact Person Rule
Owner Contact Channels Validation (Email and Phone Formats)
Private Certifier Contact Details Validation (Email and Phone Formats)
Inspection Stages Selection Must Be Coherent (At Least One Stage or DA Reference)
‘Other Stages/Aspects’ Requires Details When Selected
Proposed Building Work Description Required and Not Generic

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How to Fill Out QLD Form 18 (s143A(3)) Online for Free in 2026

What the AI walks you through.

Go to Instafill.ai and upload the Form 18 PDF (or select it from the form library if available).
Let the AI detect and map the fields, then confirm you are completing “Notice to the owner (where owner is not the client) that a private certifier has been engaged.”
Enter the property details: street address, state/postcode, lot and plan details, and the local government area.
Fill in the owner’s details: full name (and company/contact person if applicable), phone numbers, email, and postal address.
Complete the description of the proposed building work and specify the inspection stages covered by the fee (foundation/excavation, footings, slab, frame, final, and any other stages/aspects).
Enter the private certifier’s details: certifier name, company/contact person (if applicable), contact information, postal address, and licence number, plus the date of engagement.
Review for completeness and accuracy, then apply the private certifier’s signature and signature date, and download/send the completed Form 18 to the owner.

Common Mistakes in Completing QLD Form 18 (s143A(3))

The ones the AI is built to catch.

Not checking the ‘Notify owner (send to owner)’ box

People often skip the initial selection because it looks like a heading rather than a required confirmation. If it’s left unchecked, it can be unclear whether the form is actually being issued to the owner (who is not the client), which may create compliance and audit issues. Always confirm the form’s purpose by ticking the notification box before completing the rest of the fields. AI-powered tools like Instafill.ai can flag unticked required checkboxes and prevent submission with missing confirmations.

Using the wrong party’s details (owner vs client vs certifier)

A frequent error is entering the client/builder’s details in the Owner’s details section, especially when the owner is not the person managing the project. This can result in notices being sent to the wrong party and may undermine the legal requirement to notify the actual owner within the required timeframe. Verify ownership from title/rates notice and ensure the Owner’s details are the legal owner, not the applicant or builder. Instafill.ai can help by mapping data to the correct fields and warning when roles appear inconsistent.

Incorrect or incomplete ‘Date of engagement’ (wrong format or wrong date)

Many people enter the date the form was signed or sent instead of the date the certifier was engaged, or they use a non-AU format (MM/DD/YYYY). This matters because the legislation references timeframes (e.g., notice within 15 business days after engagement starts), and an incorrect date can create apparent non-compliance. Use DD/MM/YYYY and confirm the engagement start date from the contract/appointment letter. Instafill.ai can enforce date formatting and prompt you to confirm the correct event date.

Leaving inspection stages blank or selecting stages that don’t match the project class

Users often forget to tick the relevant inspection stages (foundation/footings/slab/frame/final) or they tick a generic set without considering whether the work is a class 1a/10 project versus “all other classes” tied to the development approval. This can cause disputes about what the fee covers and confusion about mandatory inspections. Tick only the stages covered by the engagement/fee and align them with the development approval requirements; if unsure, cross-check the approval conditions. Instafill.ai can help validate that at least the expected stages are addressed and prompt for missing stage selections.

Checking ‘Other stages/aspects’ but not describing them (or describing them without checking the box)

A common mismatch is selecting ‘Other stages/aspects’ and leaving the details field empty, or writing extra stages in the details area without ticking the ‘Other’ checkbox. This creates ambiguity about what is included in the fee and what inspections are expected. If ‘Other’ applies, provide clear, specific items (e.g., waterproofing inspection, pool barrier inspection, retaining wall) and ensure the checkbox and details field are consistent. Instafill.ai can detect conditional-field dependencies and require the details when ‘Other’ is selected.

Incomplete property description (missing lot/plan or using an informal description)

People often provide only a street address and omit lot and plan details, or they enter informal identifiers (e.g., “behind the shops”) that don’t uniquely identify the land. The form explicitly requires identification of all land subject to the application, and missing lot/plan can delay processing or create legal uncertainty. Use the title documents or rates notice to enter the correct Lot and Plan (e.g., Lot 12 on SP123456) and attach a list if multiple lots apply. Instafill.ai can standardize lot/plan formatting and remind you when required land identifiers are missing.

Wrong local government area (LGA) or leaving it blank

Applicants frequently confuse the suburb with the council/LGA name, especially in areas where suburb boundaries don’t match council boundaries. An incorrect LGA can lead to misrouting, delays, or inconsistencies with council records. Look up the property’s council/LGA using the rates notice or the council’s property search and enter the full LGA name. Instafill.ai can help by suggesting LGAs based on the address and flagging mismatches.

Vague ‘Description of proposed building work’

Many entries are too generic (e.g., “renovation” or “new build”) and don’t describe scope, type, or key elements, which makes it harder to align inspections and approvals. Vague descriptions can trigger follow-up requests and slow down certification and council archiving. Provide a concise but specific description (e.g., “New single detached dwelling (Class 1a) with attached garage (Class 10a), slab-on-ground, including retaining wall and pool barrier”). Instafill.ai can prompt for missing scope elements and help format a complete, consistent work description.

Missing or incorrect certifier licence number

People sometimes enter an internal company reference, an expired number, or leave the licence number blank. This can invalidate the credibility of the notice and may cause compliance checks to fail or require re-issue of the form. Enter the certifier’s current QBCC-issued licence/registration number exactly as recorded and double-check digits. Instafill.ai can validate number patterns and reduce transcription errors.

Contact details errors (email/phone/postal address) that prevent delivery

Typos in email addresses, missing digits in phone numbers, or incomplete postal addresses are extremely common, especially when copying from signatures or old records. The form states correspondence will be mailed to the provided address; incorrect details can mean the owner never receives the notice, creating compliance risk and project delays. Verify contact details against reliable sources (company records, title/rates notice, engagement contract) and include unit/PO Box/suburb/state/postcode as applicable. Instafill.ai can automatically format phone numbers, validate emails, and standardize addresses to reduce undeliverable correspondence.

Signature/date issues (unsigned form, wrong signer, or date mismatch)

Forms are often submitted without a signature, signed by an unauthorized staff member, or dated inconsistently with the engagement date. This can lead to rejection, rework, and questions about whether the notice was properly issued within statutory timeframes. Ensure the private certifier signs the form (or an authorized signatory where permitted) and date it accurately in DD/MM/YYYY. If the form is a flat non-fillable PDF, Instafill.ai can convert it into a fillable version and help ensure signature/date fields are completed before sending.

Frequently Asked Questions About QLD Form 18 (s143A(3))

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This plan is for your QLD Form 18 (s143A(3)): your own AI agent fills it as often as 5 times a month. To fill other forms and upload your own, choose a Professional plan from your account.

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How does the AI fill out QLD Form 18 (s143A(3))?

You answer a few questions in plain words, or upload a document you already have. The AI reads what you give it and puts each answer into the right field of QLD Form 18 (s143A(3)), on every page, in seconds. It checks the answers against the form's own rules, and you review and change anything before you download, print or sign.

What happens to my information?

It is encrypted in transit and at rest, and it is never used to train AI.

How complex is QLD Form 18 (s143A(3)) to fill out?

QLD Form 18 (s143A(3)) has a Form Complexity Index of 45 out of 100, in the basic tier: 41 fillable fields across 2 pages. Instafill.ai's AI fills it in under a minute, with every field there for you to review before you download.

What is Form 18 used for?

Form 18 is a notice to the building owner that a private certifier has been engaged to assess and inspect proposed building work. It is the approved form under section 143A(3) of the Building Act 1975 (Qld).

Who needs to complete and send Form 18?

The private certifier must give Form 18 to the owner when the certifier is engaged by a client who is not the owner (for example, a builder or designer). The form is sent to the owner to inform them of the certifier’s details and role.

When does Form 18 have to be given to the owner?

The private certifier must give the owner Form 18 within 15 business days after the engagement starts, unless the certifier has a reasonable excuse. The “date of engagement” field should match when the engagement began.

Does the owner have to sign Form 18?

No—Form 18 is signed by the private certifier. The owner’s details are included for correct identification and correspondence, but the owner does not sign this notice.

What property information is required in Section 1 (Property description)?

You must provide the street address (including suburb/locality and postcode), the lot and plan details (e.g., SP/RP), and the local government area. If there isn’t enough space for lot/plan details, attach a separate list.

Where can I find the lot and plan details needed for the form?

Lot and plan details are usually shown on title documents or a rates notice. If the plan is not registered by title, provide the previous lot and plan details.

What should be written in Section 3 (Description of proposed building work)?

Provide a concise description of the building work (e.g., “new single detached dwelling,” “rear extension and renovation,” “new garage/shed,” or “new swimming pool and fencing”). Include enough detail to clearly identify the scope of work being certified.

Which inspection stages should be ticked, and what does “Other stages/aspects” mean?

Tick the stages covered by the certifier’s engagement/fee (commonly foundation/excavation, footings, slab, frame, and final for class 1a and class 10 work). Use “Other stages/aspects” to list any additional inspections not already shown (and add details in the space provided).

Does the fee on Form 18 include extra inspections the owner requests later?

No—the form notes that the fee does not include additional certifying functions requested by the owner under an Additional certification notice (Form 31). If the owner requests extra functions, the owner is responsible for the reasonable costs.

What details about the private certifier are required in Section 4?

You must include the certifier’s full name, company name (if applicable), contact person (if applicable), phone numbers, email, postal address, and licence number. These details allow the owner to contact the certifier and confirm their credentials.

What if the owner wants copies of inspection documentation during the build?

The owner can request inspection documentation before the final stage inspection by completing Form 35 (Building owner request for inspection documentation) and giving it to the private certifier. The certifier must provide the requested documents within 5 business days after receiving Form 35 (with some eligibility limits for engagements before 1 October 2020).

How can an owner request additional certifying functions (like an extra inspection)?

If the owner did not engage the certifier, the owner may request additional certifying functions using Form 31 (Additional certification notice), subject to the rules in section 143B of the Building Act 1975. Timing requirements apply (including providing copies to the client and certifier within specified business days).

Can AI help me fill out Form 18 accurately?

Yes—AI tools can help extract details from your documents and place them into the correct fields to reduce errors and save time. Services like Instafill.ai use AI to auto-fill form fields accurately based on the information you provide.

How do I fill out Form 18 online using Instafill.ai?

Upload the Form 18 PDF to Instafill.ai, then upload or paste the relevant details (owner info, property address, lot/plan, certifier details, licence number, and engagement date). Instafill.ai can auto-map your information into the correct fields, after which you review, edit if needed, and export the completed form for signing and sending to the owner.

What if my Form 18 PDF is not fillable (a flat PDF)?

If the PDF is not fillable, you can use Instafill.ai to convert a flat, non-fillable PDF into an interactive fillable form and then auto-fill it. This helps avoid printing/scanning and reduces manual typing errors.

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