Time bars: the clause that quietly costs subcontractors their money

Construction was again the industry with the most company insolvencies in Australia last financial year. In 2025–26 it accounted for 24.5% of all external administration appointments, well ahead of the next industry, according to ASIC's insolvency data.

Cash flow and contract terms sit at the heart of a lot of those failures. And most subcontractors sign contracts with clauses that can quietly strip away their right to get paid or to claim time. The one I would put at the top of the list is the time bar.

None of this is hidden. It is just easy to miss when you are busy doing the work.

What a time bar actually does

A time bar is a clause that says: if you do not give written notice, or lodge a claim, within a set period, you lose the right to make that claim. Not reduced. Gone. They usually sit on extensions of time and variations, but they also turn up in latent conditions, progress payment and dispute clauses (Construction Law Made Easy).

The standard forms show how it works. Under AS 4000, the contractor is only entitled to an extension of time if it submits a written claim within 28 days of when it should reasonably have become aware of the cause of the delay (Construction Law Made Easy). The clock starts when you should have known, not when the delay ends and not when you get back to the office to do the paperwork.

Most subcontracts are built from an amended head contract, and the amendments rarely make the windows longer. In the fictional AS 4000 subcontract we use for the ContractLens sample report, the extension of time notice window is 10 business days, with no cure period and a clause saying a late claim is "forever barred". On a busy site with overlapping delays, one missed notice loses the whole claim.

Will a court really enforce it?

Generally, yes. Where a time bar is written clearly, it will usually be enforced even if the result is harsh or the bargaining power was one-sided (K&L Gates). Courts do not see it as their job to rewrite a bargain to make it more sensible (Construction Law Made Easy).

Unamended AS 4000 does give the superintendent a reserve power to extend time even when no valid claim was made. But it is a discretion, it is often amended or deleted in subcontracts, and you cannot build a business on hoping someone uses it in your favour (Sitepack).

Unfair contract terms: a backstop, not a plan

Since 10 November 2023 the unfair contract terms regime in the Australian Consumer Law covers a much wider range of small business standard form contracts, including many subcontracts. A time bar can be unfair if it causes a significant imbalance, is not reasonably necessary to protect the legitimate interests of the party relying on it, and would cause detriment if applied (K&L Gates).

The obvious target is a mismatched chain. Lawyers have pointed out that a subcontractor given seven days to notify a delay, when the head contractor has 28 days to pass it up the line, is more exposed to challenge than a time bar that mirrors the upstream contract (Legal 500). Western Australia goes further: its security of payment legislation lets a decision maker find a notice-based time bar unfair where compliance was not reasonably possible or would be unreasonably onerous (K&L Gates).

That is useful to know. But arguing after the event that a clause was unfair is slow, expensive and uncertain. The cheap fix is before you sign.

In Queensland, know the payment clock on both sides

Payment is where Queensland law gives subcontractors real protection, whatever the contract says. Under the BIF Act and QBCC Act (QBCC):

• A subcontract cannot set a payment term longer than 25 business days after the payment claim. A longer term is void and the default of 10 business days applies.
• Pay-when-paid clauses are void.
• If the head contractor wants to pay less than you claimed, it must give you a payment schedule within 15 business days, or sooner if the contract says so.

If no payment schedule arrives in time, the full amount claimed becomes payable on the due date (Holding Redlich). The flip side is that your own claims run to a clock too: you can only give one payment claim for each reference date in the contract (QBCC). The Act protects you on payment. It does not rescue a variation or delay claim you never notified.

What to check and negotiate before you sign

• Find every time bar. Search the contract and the special conditions for "notice", "within", "barred", "condition precedent" and "deemed". List each one with its window.
• Compare it with the head contract. Ask for the head contract's notice periods. Your window has to be shorter than the head contractor's so they can pass your notice up the chain, but it should be in proportion. Seven days against an upstream 28 is the kind of gap worth pushing back on (HHG Legal).
• Ask for a longer window and a no-prejudice carve-out. For example, 15 business days for extension of time notices, and a clause saying late notice does not bar the claim unless the head contractor was actually prejudiced by the delay.
• Pin down what counts as notice. Who it goes to, whether email is enough, and what it must contain. "I told the site manager on Tuesday" will not save a claim.
• Check the definition of business day. Public holidays, the Christmas shutdown and rostered days off can shrink a short window further.
• Raise it in tender clarifications, not after award. That is when you have leverage. Once the contract is signed, the windows are what they are.
• Price what you cannot change. If the head contractor will not move, the risk of a lost claim is a cost. Put it in the number or decide whether the job is worth it.

Then run it as a system, not a memory test

• Record every direction the day it happens: an email, a photo, a site diary entry or a voice note.
• Send a short written notice of intention to claim the same day. You can price it later; most contracts treat the notice and the priced claim as separate steps, and missing either can bar you.
• Keep one register that links each direction, notice, claim and response, with the deadline for each.
• Review the register every week with the site team, and escalate anything with a clock running.

Where ContractLens fits

This is why I built ContractLens for Australian subcontractors, consultants and small builders. Upload your contract and you get a plain-English commercial risk report focused on the clauses that most often cost subcontractors money: variations, extensions of time and time bars, payment claim procedures, indemnity caps, latent conditions and termination. Every review includes a free 30-minute call to walk through it.

Run your contract through before it costs you.

Upload a contract See the sample report (PDF)

Once the contract is signed, the notice clock is the problem. That is why we built Varipack: your crew records the site instruction when it happens, and it tracks the notice dates in your contract so a claim goes in before the time bar runs out. (Disclosure: Sitepack and Varipack are WPC Consulting products.)

This article is general commercial information, not legal advice. Contract terms and state laws differ. If the amounts are significant, get advice from a construction lawyer before you sign or before you rely on a time bar argument.