What makes a valid signature under Australian law

A signed contract sitting in your inbox is not automatically enforceable. If the signature on it lacks identity or intent — or if the execution process skipped a required step — you may have nothing more than a piece of paper. For most everyday commercial agreements, Australian law is flexible about what counts as a signature. But the rules tighten considerably for deeds, company documents, and some document types that require witnessing. Getting the distinction right protects deals, limits disputes, and avoids the cost of re-execution.

What counts as a signature

Australian law treats a signature as any mark or method that does two things: identifies the person signing, and demonstrates that person's intention to be bound by the document. There is no requirement that the signature be a cursive handwritten name. A typed name at the foot of an email, a mark applied by stylus, a click on an "I accept" button, or a digital certificate embedded in an eSigning platform can each qualify — provided the method reliably connects the person to the document and indicates approval.

Courts examining a disputed signature focus on those two elements: identity and intent. A signature that clearly meets both in the circumstances of the transaction will ordinarily be treated as valid. One that leaves either element in doubt creates an enforceability gap that the other side can exploit.

When a signature makes the contract binding

Signing is the final act of agreement, but it only works if the underlying contract is complete and authorised. For a signed business contract to be legally binding, the following elements generally need to be present:

• Agreed terms: the parties must be agreed on the essential terms — what is to be done, by whom, when, and for what price or consideration.
• Intention to create legal relations: in a commercial context this is usually presumed, but arrangements between related parties or family members can raise the question.
• Legal capacity and authority: an individual must have capacity to contract; a company representative must have actual or apparent authority to sign on the entity's behalf.
• Consideration (for ordinary contracts): typically an exchange of value — payment, a promise to perform, a licence granted. Consideration is not required for a deed.
• Required formalities: some documents carry additional requirements — specific execution blocks, witnessing, particular wording (especially deeds).

The signature does not cure defects in these elements. A person signing under duress, or a director signing without board authority, may not produce a binding result regardless of how the signature looks.

How a company executes documents under the Corporations Act

For Australian companies incorporated under the Corporations Act 2001 (Cth), the most reliable way to execute a contract or deed is under s 127. This section allows a company to execute a document without using a common seal by having it signed by:

• two directors; or
• one director and one company secretary; or
• a sole director who is also the sole company secretary, signing alone.

The practical benefit of s 127 execution is the protection it extends to the other side. Under ss 128 and 129 of the same Act, a person dealing with a company in good faith can assume that a document appearing to be executed under s 127 has been validly executed, without needing to check internal delegations, board resolutions, or the company's constitution. That assumption significantly reduces counterparty risk in B2B contracts.

Since the Corporations Amendment (Meetings and Documents) Act 2022 took effect, s 127 has been technology-neutral. Companies can now execute documents, including deeds, using electronic means — the method must identify each signatory and indicate their intention in respect of the information being signed, and must be as reliable as appropriate for the purpose. Split execution (different signatories signing at different times or on different copies) is also permitted under the amended provisions. The amendments applied from 1 April 2022 and are permanent.

Where a company uses the common seal instead of s 127 execution, the company's constitution typically prescribes the requirements. Most modern companies execute commercially without a seal, relying on s 127.

Electronic signatures — when they work and when they do not

The Electronic Transactions Act 1999 (Cth) and its state and territory equivalents (including the Electronic Transactions Act 2000 (NSW), the Electronic Transactions (Victoria) Act 2000, the Electronic Transactions (Queensland) Act 2001, and corresponding legislation in each other jurisdiction) establish that an electronic signature satisfies a legal requirement for a signature where:

1. the method used identifies the person and indicates their intention in respect of the information communicated;
2. the method is as reliable as appropriate for the purpose, having regard to all the circumstances (including any relevant agreement between the parties); or the method is proven in fact to have fulfilled those functions; and
3. the other party consents to the requirement being met electronically (where the requirement is owed to a private person rather than a Commonwealth entity).

Under s 10 of the Electronic Transactions Act 1999 (Cth), these conditions are the complete test. Most commercial eSigning platforms — including those that capture IP address, timestamp, authentication records, and tamper-evident certificates — are designed to meet the reliability limb as a matter of course for ordinary business contracts.

Where electronic signatures do not work. The Act's protections do not extend universally. Wills and testamentary instruments, certain real property dealings, and some statutory forms remain outside the scope of the electronic execution framework, either under Commonwealth or state-level exclusions. These categories should always be executed in wet ink unless a specific state law has expressly permitted electronic execution for that document type in that jurisdiction. If you are unsure whether a document you are executing falls into an excluded category, assume wet ink is required until you have confirmed otherwise.

Deeds — why the formalities matter more

A deed is a document that is binding without consideration. It is commonly used for releases, settlements, confidentiality obligations where no payment changes hands, equity grants, and some guarantees. The absence of a consideration requirement makes deeds useful in specific commercial situations, but it comes with stricter execution rules.

For a document to operate as a deed, it generally must:

• be clearly expressed to be executed "as a deed" (the wording in the document matters);
• be signed by the executing party;
• be witnessed in jurisdictions that require it for individual signatories; and
• be delivered (which, in a commercial context, usually means the executing party intending the deed to take immediate effect).

Witnessing requirements for individuals signing a deed vary across Australian states. In New South Wales, s 38 of the Conveyancing Act 1919 (NSW) requires that a deed be attested by at least one witness who is not a party to the deed. Victoria does not impose a statutory witness requirement for individual deed execution under s 73 of the Property Law Act 1958 (Vic), which instead focuses on signature or mark. Queensland similarly does not require a witness under s 45 of the Property Law Act 1974 (Qld). Other jurisdictions have their own requirements that must be checked.

Because the rules differ, the safest approach for a deed that will be executed across multiple states, or where the governing law is uncertain, is to have the individual signatory witnessed by a person who is present, independent, and adult — regardless of whether the specific state law strictly requires it.

Electronic execution of deeds. NSW has introduced a pathway for electronic deeds under the Conveyancing Act 1919 (NSW) (see s 38A), and the 2022 amendments to the Corporations Act allow companies to execute deeds electronically under s 127. However, for deeds executed by individuals outside NSW, electronic execution is not uniformly available. Check the applicable state legislation before executing a deed electronically.

Remote witnessing

A witness is usually required to observe the signing in real time. Several states have enacted provisions for remote witnessing by audio visual link. In New South Wales, Part 2B of the Electronic Transactions Act 2000 (NSW), inserted by the Electronic Transactions Amendment (Remote Witnessing) Act 2021 (NSW), permanently permits witnessing via audio visual link for documents that require a witness under NSW law. The witness must observe the signatory signing in real time, and the witness may countersign a counterpart or the scanned signed copy as soon as practicable after witnessing. Equivalent provisions are not uniform across all states, so if you are executing a deed or witnessed document in another jurisdiction, confirm whether remote witnessing is permitted for that document type before proceeding.

Signing on behalf of another party

A director signing for a company, an employee signing for their employer, or an attorney acting under a power of attorney must each have clear authority before the signature binds the principal. For company signatories, the s 127 execution block creates the presumption of authority. For individual agents, the authorising instrument — a board resolution, a delegation of authority, or a registered power of attorney — should be on file and produced promptly if challenged.

When signing as agent, the execution block should make the capacity explicit: "signed by [Name] for and on behalf of [Principal]". Signatures that obscure the agency relationship can create personal liability for the signatory or ambiguity about who is bound.

Counterparts and document integrity

Where parties sign separate copies of the same document (counterparts), each copy becomes part of the same agreement when the last party signs — provided the document contains a counterparts clause authorising this. Counterparts clauses are standard in well-drafted commercial agreements and should include express permission for signed copies to be transmitted electronically. Once execution is complete, circulate a single fully executed version to all parties so everyone holds the same record.

Before sending any document for execution, lock the file (usually a PDF with editing restrictions) to preserve page integrity. If amendments are necessary after the document has been sent, do not mark up a circulating copy informally. Instead, issue a clean revised version for re-execution, or use a formal deed of variation if the original is already executed. Parties should record any agreed last-minute changes in writing and initial the amended clauses, with the final clean executed copy distributed immediately.

How Artificer Legal can help

Execution mistakes are among the most common — and most avoidable — sources of contract disputes. The right advice at the drafting and execution stage is far less costly than litigation over a defective signature. An Artificer Legal solicitor can assist by:

• advising on the correct execution block for your entity type and the document you are signing (company under s 127, individual, trustee, partnership, or other structure);
• reviewing deed execution requirements for your specific jurisdiction and confirming whether witnessing is needed, who qualifies as a witness, and whether electronic or remote execution is available;
• drafting or reviewing execution clauses, counterpart provisions, and deed-of-variation instruments;
• preparing board resolutions and authority documents to support signatories acting on a company's behalf;
• advising on the Electronic Transactions Act framework and whether a particular document type falls within or outside its protections; and
• assisting when a signature is challenged — including assessing whether ratification, re-execution, or a different remedy is the right path.

Reach out to Artificer Legal for a consultation before you circulate a document for execution in a situation you are not certain about — early advice prevents defects that are far harder to cure once all parties have signed.

The single thing most likely to determine whether a signing holds up

Most signature disputes are not about what the mark looks like. They are about whether the person who applied it had authority to bind the party named in the document, and whether the execution formalities matched the document type. A director signing a deed on behalf of a company, without using s 127, without a counterpart clause, and without checking the witnessing requirement for the state in which the individual co-signatory is located, can produce a document that is defective in multiple respects simultaneously — none of which are obvious until the other side raises them.

The underlying rules are not complex: match the execution block to the entity type; check the witnessing rule for the jurisdiction; use s 127 for company execution and keep the 2022 electronic amendments in mind; and never modify a document informally after it has been sent for signature. Those four habits eliminate the vast majority of execution risk in ordinary commercial practice.