Change Order in Australia: Template and Key Clauses (2026)

A change order in Australia records an agreed change to an existing contract: a new scope, a different price, a revised timeline, or all three. It is common in construction, engineering, IT and services work. The question that matters in Australia is whether the change is validly agreed, valued the way the contract requires, and handled correctly for payment and tax, with the added point that construction payment law differs from state to state. This guide sets out the Australian law that applies, the key clauses, and a drafting skeleton. It is general information, not legal advice; take Australian advice before signing a live deal. ## What is a change order in Australia? A change order, often called a variation or change request, is a written amendment to a contract already in force. It modifies the existing contract rather than creating a new one: adding or removing work, adjusting the price, or moving dates. In construction and project contracts it is usually issued under a variations clause in the main agreement, which sets out who can order a change, how it is valued, and how the time and cost impact is handled. ## What law governs change orders in Australia? Australian contract law is based on common law, so there is no single federal change-order statute. The change is governed by the main contract, general contract principles, and state-based payment rules: - Agreement and consideration. A contract can be varied by agreement, but at common law a variation generally needs fresh consideration or a valid contractual mechanism. A one-sided change that adds work without any adjustment can be unenforceable unless the main contract already provides for it.

• The variations clause. Most well-drafted Australian project contracts contain a variations mechanism. If it does, follow it: the change order should be issued, valued and timed as the clause requires. If it does not, the change rests on fresh agreement.
• Security of payment. For construction work, each state and territory has its own Security of Payment Act, for example the Building and Construction Industry Security of Payment Act 1999 in New South Wales, with equivalents in other states. These support progress claims and provide fast adjudication of payment disputes, and they are not identical across states. Variations feed into what is claimable, so a clear, agreed change order matters for cash flow and for any adjudication. Confirm which state's Act applies.
• GST. A change in scope or value changes the taxable supply, so Goods and Services Tax applies to the revised value where the supplier is registered. State whether figures include or exclude GST. ## Key clauses in an Australia change order - Reference to the original contract: identify the main contract by date and parties.
• Description of the change: the exact scope added, removed or altered.
• Price adjustment: the revised amount, how it was valued, and the GST treatment.
• Time adjustment: any extension of time or revised milestones.
• Effect on the rest of the contract: confirm all other terms continue unchanged.
• Consideration: make clear what each side gives, so the variation holds at common law.
• Approvals and authority: who may approve the change on each side.
• Security of payment: for construction, how the change feeds into payment claims under the relevant state Act.
• Signatures and date. ## Getting the change validly agreed The common dispute is whether a change was agreed or was just extra work someone assumed would be paid for. In Australia, the safe route is a signed change order issued the way the main contract allows, with a clear price and time impact, before the changed work starts. Where the contract has a variations clause, use it. For construction work, a clean change order supports any later payment claim or adjudication under the state Security of Payment Act, and the strict timeframes in those Acts make good records essential. ## A simple drafting skeleton 1. Title and change order number

2. Reference to the original contract (parties and date)
3. Background and reason for the change
4. Description of the change in scope
5. Revised price and GST treatment
6. Revised timeline or extension of time
7. Consideration and confirmation the variation is agreed
8. Effect on remaining terms (all else unchanged)
9. Approvals and authority
10. Security of payment note (relevant state Act)
11. Signatures and date ## Common mistakes to avoid - Doing extra work on a verbal instruction, with no signed change order, and then struggling to be paid or to support an adjudication claim.

• Ignoring the variations clause in the main contract and inventing a different process.
• Assuming one state's Security of Payment Act applies when another state's rules and timeframes govern the project.
• Overlooking the GST impact of a changed scope or value. ## Keeping change orders under control If you run many projects, the hard part is not one change order. It is tracking which contracts have been varied, how many times, what the running revised price and timeline are, which state's payment rules apply, and how each change feeds into payment claims. Drafting from a tuned template, flagging risky clauses, and keeping a clean version history is what an AI contract workspace can hold in one place. Adira is built for this, with per-clause risk review, plain-English clause editing and a live activity timeline that doubles as version history. It is India-first today, with Australia and other jurisdictions on its roadmap, so confirm local depth before relying on it for state security-of-payment detail. More at Adira. The law above stands on its own. ## Bottom line A change order in Australia is an amendment to a live contract under common law. Agree it in writing, support it with consideration or a valid contractual mechanism, follow the variations clause where there is one, and price the GST correctly. For construction work, remember that the Security of Payment Act differs by state and underpins your payment claims. Take Australian advice on a real deal.