Most construction contracts require written notice of a cost claim within a specified period. Missing the deadline can extinguish the entitlement entirely, even where the underlying claim is valid. Australian courts have consistently upheld these time-bar provisions.
A claim for a variation: if you are framing your cost increase as a variation, notice is typically required at or shortly after the event giving rise to the variation.
A claim under a rise and fall clause: the clause may have its own notice requirement separate from the general variation provisions.
A claim for an extension of time: if cost increases are causing delay, a separate notice may be required.
Written notice within 28 days is the general window for variation and time claims. For cost claims framed as variations, notice must be given before the variation is carried out in most circumstances.
Similar notice obligations to AS 4000. Special conditions in government AS 4300 contracts often strengthen these requirements. Always read the Special Conditions alongside the General Conditions.
Written notice within 14 days is common in standard versions. Check Special Conditions for modifications.
The contractor must notify the Project Manager within 8 weeks of becoming aware of the compensation event. This is a strict deadline. Missing it eliminates the entitlement to additional cost, though the contractor may still be entitled to time. The 8-week period runs from when the contractor became aware, not from when they quantified the impact.
Clause 20 covers adjustments to contract price. Written notice is required, and time limits are specified in the Contract Particulars. Check the Contract Particulars carefully.
Many standard subcontracts include notice requirements that are stricter than the head contract. A subcontractor who has a valid cost increase claim can lose it entirely by missing a notice deadline in their subcontract, even if the head contractor is successfully recovering the same cost from the principal.
Blaze Business & Legal
Need advice on your specific position?
Three fixed-fee services covering your legal, cost, and business situation. Rachelle Hare and Shannon Drew directly.
Must be in writing. Email generally satisfies this requirement but check your contract for specific delivery requirements.
Should identify: the event giving rise to the claim, the clause you are relying on, the nature of the impact (time and/or cost).
You do not need to quantify the claim in full at the notice stage in most contracts. You need to identify the event and the impact. Quantification follows.
Keep a copy of every notice you send, with evidence of delivery.
A missed notice deadline is not always fatal. Arguments that may be available include: the principal has waived the notice requirement by accepting previous claims without raising the notice issue; the principal’s conduct has estopped them from relying on the time-bar; the notice period has not yet started because you were not aware of the event until a later date.
If you have missed a notice deadline on a significant claim, get legal advice before doing anything else.
Blaze Business & Legal
Three fixed-fee services for construction businesses working through the cost crisis. Rachelle Hare and Shannon Drew directly, from the first conversation.
Rachelle Hare is a construction lawyer and business adviser with 25 years of experience, including in-house roles at Thiess, Laing O’Rourke, Acciona, DHA, and UGL. She advises construction businesses on contracts, cost recovery, risk, procurement, commercial strategy, and business structuring across Queensland and Australia.
