How to Collect Unpaid Invoices from a Head Contractor in Australia (Complete 2026 Guide)

When a head contractor or builder doesn’t pay your invoice, waiting around costs you cash flow and time. This guide walks you through every step to collect what you’re owed—including when and how to use Australia’s Security of Payment legislation to force a formal response.

How do I know if my invoice is actually overdue?

First, check your payment terms. Most construction contracts specify payment within 7, 14, or 30 days of invoice. If the date has passed and you haven’t received payment, it’s overdue.

Keep records of:

• Invoice date and amount (including GST)
• Work completion date
• Agreed payment terms
• All correspondence with the head contractor
• Any proof of delivery (email read receipts, signed delivery dockets)

Don’t assume the invoice was lost. Contact the head contractor’s accounts team directly—sometimes invoices sit in the wrong inbox.

What should I do before taking legal action?

Send a formal written demand for payment. This isn’t legally required before a Security of Payment claim, but it creates a clear record and often prompts immediate payment without further steps.

Your demand letter should include:

1. Your business name, ABN, and contact details
2. The exact invoice number(s) and amount owing
3. Description of work completed
4. Original invoice date and due date
5. A clear statement that payment is now overdue
6. A request for payment within 5–7 business days
7. Your bank details for payment

Send it by email (with read receipt) or registered mail. Keep a copy. A professional demand letter often resolves the issue without further action.

What is Australia’s Security of Payment Act and when can I use it?

Every Australian state and territory has a Security of Payment Act. These laws give subcontractors, tradies, and suppliers a fast-track way to recover unpaid invoices without going to court.

The key feature: a head contractor or developer must respond within 10 business days (or their state’s timeframe) with either payment or a detailed reason why they won’t pay. If they don’t respond properly, you can force adjudication—an independent referee decides the claim in your favour within weeks, not months.

Here’s the legislation by state:

State/Territory	Act	Respondent Response Deadline
NSW	Building and Construction Industry Security of Payment Act 1999	10 business days (s.14)
QLD	Building Industry Fairness (Security of Payment) Act 2017	10 business days (s.20)
VIC	Building and Construction Industry Security of Payment Act 2002	10 business days (s.14)
WA	Construction Contracts Act 2004	10 business days (s.11)
SA	Building and Construction Industry Security of Payment Act 2009	10 business days (s.12)
TAS	Building and Construction Industry Security of Payment Act 2009	10 business days (s.13)
NT	Construction Contracts (Security of Payments) Act 2004	10 business days (s.12)
ACT	Building and Construction Industry (Security of Payment) Act 2009	10 business days (s.12)

You can only use the Act if you’ve supplied goods, services, or labour under a construction contract. Unpaid invoices from subcontractors, labourers, and material suppliers all qualify.

How long do I have to lodge a payment claim?

This varies by state, but the standard timeframe is 12 months from the date you last supplied labour or materials. Some states allow claims up to the end of the contract period plus a set number of months.

Don’t wait. The longer the invoice sits, the harder it becomes to argue it was rightfully earned. Lodge your claim as soon as you’ve sent a demand letter and allowed reasonable time for a response.

What information must I include in a Security of Payment payment claim?

The claim is a formal document submitted to the head contractor (and usually to the principal/developer too). It must include:

• Your name and contact details
• The head contractor’s or developer’s name and address
• Details of the construction work or goods supplied
• The invoice number(s), date(s), and amount due (including GST)
• Identification of the contract (project name, address, date)
• The amount claimed and the due date
• A statement that the claim is made under the Security of Payment Act
• Supporting documents (invoices, quotations, delivery dockets, photographic evidence of work)

The claim must be clear, detailed, and professional. Vague or incomplete claims can be rejected on procedural grounds, delaying recovery. You can file a payment claim online using a template that’s already compliant with your state’s legislation, saving time and reducing errors.

How do I formally serve the payment claim?

Most state Acts require the claim to be served on the head contractor personally, by email, or by post to their registered office or last known address. Check your state’s Act for the exact method.

Record the date and method of service. This is critical: the 10 business day response clock only starts when the claim has been properly served. If the head contractor claims they never received it, you need proof.

Email with read receipt is the safest method. Alternatively, use registered post or a courier service that tracks delivery.

What happens if the head contractor doesn’t respond within 10 business days?

If they don’t issue a payment schedule or respond to your claim, they’ve failed their statutory obligation. You can immediately move to adjudication—a fast, binding dispute resolution process.

Don’t wait beyond the 10 days hoping they’ll pay. The sooner you lodge an adjudication application, the sooner you get a decision.

What is adjudication and how do I apply?

Adjudication is a statutory process where an independent adjudicator (usually a construction lawyer or former building official) reviews your claim and the head contractor’s response within 20–30 days and makes a binding determination on what’s owed.

It’s much faster and cheaper than court. To apply, you’ll need to:

1. Lodge an adjudication application with your state’s relevant authority (varies by state: some use a nominating authority, others accept direct referral)
2. Pay a lodgement fee (typically AUD $200–$600 depending on your state and claim size)
3. Provide copies of the payment claim, proof of service, and any response from the head contractor
4. Submit your supporting case (invoices, correspondence, photos, witness statements)

The head contractor then has a set period (usually 10 business days) to file their response and evidence. The adjudicator reads both sides and issues a determination.

What if the adjudicator rules in my favour?

The adjudicator’s decision is binding and enforceable immediately—even if the head contractor disagrees and wants to challenge it later in court. The head contractor must pay the amount determined, plus any interest and costs awarded.

If they don’t pay within the timeframe set by the adjudicator (usually 5 business days), you can enforce the determination through:

• Court order: File the determination as evidence and apply for judgment
• Debt recovery action: Engage a debt collector or lawyer to pursue enforcement
• Director penalty notice (if applicable): In some states, you can pursue the company director personally if insolvency is involved

What if the head contractor disputes the claim?

They’ll lodge a payment schedule or adjudication response explaining why they say the invoice is wrong—for example, because work wasn’t completed, was defective, or was already paid.

If their objection is valid (e.g. the work genuinely wasn’t finished), the adjudicator may reduce the amount owing or dismiss the claim. This is why your supporting documents—photos, signed completion certificates, email confirmations—matter enormously.

Be prepared to respond to their arguments in your adjudication application. Don’t assume you’ll win automatically.

Can I claim interest and costs?

Yes. Under the Building and Construction Industry Security of Payment Act in most states, you’re entitled to claim interest on the overdue amount from the invoice due date until payment. Interest rates are set by legislation (typically 10% per annum or the Reserve Bank rate, whichever is higher).

You can also claim costs—adjudication fees, postage, and reasonable professional advice. Include these in your claim or adjudication application.

What if the head contractor is insolvent or dodges service?

If the company is in liquidation or administration, the adjudication process still applies, but you may rank alongside other creditors. If you can’t locate them to serve the claim, you may need legal advice on alternative service methods.

If they’re deliberately hiding assets, a debt recovery lawyer or bailiff may be needed after you have an adjudication decision or court judgment.

How much does this process cost me?

Costs vary:

• Payment claim: AUD $0–$200 to prepare (DIY or using an online service like PayClaim)
• Adjudication lodgement fee: AUD $200–$600 (state-dependent; larger claims may incur higher fees)
• Legal or professional advice: Optional; you can self-represent, but legal advice may prevent errors

For most subcontractors, the total out-of-pocket cost is under AUD $1,000. Compare that to court, which costs thousands.

How long does the whole process take?

From payment claim to adjudication decision: typically 6–8 weeks if the head contractor doesn’t pay immediately. Some claims resolve faster if they issue a payment schedule offering partial payment within the 10-day window.

Enforcement (if they don’t pay the adjudication decision) can take longer and depends on the head contractor’s willingness to pay or their financial situation.

Do I need a lawyer?

No. The Security of Payment Acts are designed to let tradies and small businesses self-represent. Many subcontractors prepare and lodge claims without legal help.

However, a lawyer or experienced construction consultant can help if:

• The head contractor files a complex dispute
• The claim involves multiple invoices or defect claims
• You need enforcement after winning adjudication
• The amount is large (e.g. over AUD $50,000)

Even a single consultation with a construction lawyer (AUD $200–$500) can clarify your position before lodging.

Bottom line: Don’t leave money on the table. When a head contractor or builder owes you, follow this process: demand letter → payment claim → adjudication. Most issues are resolved faster and cheaper than court, and the law gives you real leverage. Start now.

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Frequently Asked Questions

What's the difference between a payment claim and a statutory demand when chasing a head contractor?

A payment claim is filed under your state's Security of Payment Act (like NSW's SOP Act 1999 or QLD's BIF Act 2017) to trigger a dispute resolution process—typically adjudication. A statutory demand is a formal notice under the Corporations Act demanding payment within 21 days, which can lead to insolvency proceedings if unpaid. Payment claims are faster for construction disputes; statutory demands are broader but riskier if the contractor has grounds to dispute.

How long do I have to lodge a payment claim under the Security of Payment Act?

Timeframes vary by state. NSW allows claims within 12 months of work completion. Queensland's BIF Act requires claims within one month of when payment becomes due, unless agreed otherwise. Victoria's SOP Act has similar tight windows. Always check your contract and your specific state legislation—missing deadlines can bar your claim entirely, so act quickly.

What happens if a head contractor doesn't respond to my payment claim?

If they don't respond within the prescribed timeframe (usually 7–10 days depending on your state), you can apply for adjudication. An adjudicator will review your claim and make a determination, typically within 10–14 days. This is binding and enforceable immediately, even if the contractor disagrees. Adjudication is faster than court but doesn't stop them later challenging the amount owed.

Can I recover legal costs if I win an adjudication against a head contractor?

Generally, no. Most state Security of Payment Acts (NSW SOP Act 1999, QLD BIF Act 2017, VIC SOP Act 2002) don't award legal costs in adjudication—you bear your own. However, if you pursue enforcement through court later, costs may be recoverable depending on the judgment. Check your state's specific rules and consider cost-benefit before escalating.

What's the quickest way to actually get paid once I have an adjudication decision?

An adjudication determination is immediately enforceable. If the contractor doesn't pay within the timeframe, you can apply to court for an enforcement order or pursue debt recovery. Some contractors pay quickly to avoid further legal action. Having a clear paper trail, proper invoicing, and following your state's SOP Act procedures (NSW 1999, QLD 2017, VIC 2002, WA 2004) strengthens your position throughout.