Occupation Certificate: Interim vs Final

The Occupation Certificate (OC) is the document issued by the certifier or RBS confirming a building (or part of it) is safe and lawful to occupy. Two types exist in most Australian jurisdictions:

Interim Occupation Certificate (IOC): permits partial occupation of a completed portion of a building while other work continues.
Final Occupation Certificate (FOC): issued at full project completion and signals the build is complete.

When an IOC is used:

Phased completion: a duplex where Unit A is finished and ready to occupy while Unit B is still under construction.
Stage-by-stage builds: ground floor finished and the client wants to move in while upstairs finishing-trades continue.
Renovation living-in: client living in a habitable part of an extended house while a new addition is being completed.
Pre-completion handovers under contract: where the contract allows partial possession to commence.

An IOC is conditional. The certifier issues it only when:

The portion to be occupied is itself complete, safe, weatherproof, and meets the BCA / NCC requirements for that classification of building.
The remaining construction does not endanger the occupied portion (e.g. structural work is complete, fire separation between phases is in place).
Mandatory inspections for the occupied portion have all been passed.
Essential services (water, electricity, gas, sewer) are connected to the occupied portion.
Health and safety controls are in place separating the occupied portion from active construction.

A subsequent FOC is required at full completion. The IOC does not substitute for the FOC.

FOC issuance. The FOC is typically issued when:

All works are complete to the design and consent.
All required inspections have been conducted and passed.
Compliance certificates are in place: electrical Certificate of Compliance, gas certificate, waterproofing certificate, AS 3798 earthworks compliance report, structural engineer’s compliance certificate, fire-system certificates.
No outstanding directions from the certifier or council.

State variations:

NSW: under EP&A Act 1979 Part 6. The certifier issues IOC and FOC; council retains an enforcement role.
VIC: Building Act 1993. The Relevant Building Surveyor (RBS) issues an Occupancy Permit (broadly equivalent to OC) at completion. Interim permits are less commonly used; VIC tends to use the Certificate of Final Inspection (CFI) for non-occupancy structures.
QLD: Form 21 Final Inspection Certificate or Form 11 Notification of Completion via QBCC.
Other states: similar structures with different document names.

Why builders care about the distinction:

Contract progress claims: many residential contracts allow the final progress claim only at FOC, not IOC. Claiming on IOC may breach the contract.
Risk of partial occupation: client moving into IOC area while construction continues introduces liability exposure if they’re injured by ongoing work or if work disturbs the occupied area.
Insurance: CW insurance typically continues until FOC, not IOC. The PI / professional risk for the builder continues longer than the IOC date suggests.
Defects liability period (DLP): starts on FOC, not IOC, in most contracts. A 13-week or 12-month DLP measures from final completion.

For builders.

Confirm with the certifier early whether IOC is feasible on a staged build. Some certifiers refuse IOC on grounds of construction-zone safety.
Don’t agree to client move-in on IOC without contract language covering risk and access. A bilingual IOC handover document is wise.
Schedule the FOC independently of any IOC. The FOC is the trigger for final payment and DLP commencement.

Also known as: IOC, FOC, interim OC, final OC.

Category: Compliance / approvals / completion.

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