Company stamps and common seals, what Australian companies actually need

Company stamps sit on a lot of Australian office desks, and plenty of business checklists tell you a company "should have one". The legal position is simpler than the folklore. Under the Corporations Act 2001 (Cth), a company is not required to have a common seal or a company stamp, and most small businesses never need either.

But "no stamp required" is not the same as "no obligations". The Corporations Act imposes real duties on how your company signs documents, who can sign them, and how your company name and ACN appear on the paperwork you issue. Get those wrong and a contract or deed can fail to bind your company, or bind it when you never intended it to.

This article sets out the four obligations that actually matter: when a seal or stamp is required (and what happens if you adopt one), the signatory rules for executing documents, the rules for electronic signing, and the name and ACN display requirements. We then cover what happens if you get them wrong, a compliance checklist, and when a lawyer's help is worth the cost.

Who these obligations apply to

The obligations below apply to companies registered with ASIC under the Corporations Act 2001 (Cth), including the proprietary company (Pty Ltd) structure most small businesses operate through. They apply regardless of turnover, size or industry. There is no threshold below which a company can skip them:

• Proprietary company (Pty Ltd): the standard small business structure. It can execute documents under s 127 of the Corporations Act, including by a sole director signing alone in the circumstances set out below.
• Public company: subject to the same execution and display rules, but a sole director cannot sign alone under s 127. The two-signatory combinations apply.
• Sole traders and partnerships: not companies, and they have no ACN. The individual (or partners) sign contracts personally, and any "business stamp" is purely optional admin. The company rules in this article do not apply to them.

The first obligation: no seal or stamp is required, but a seal must comply

Under s 123(1) of the Corporations Act 2001 (Cth), a company may have a common seal. The word "may" is doing the work. The Act's own small business guide states plainly that a company is not required to have a common seal (s 7), and the note to s 123 confirms a company can make contracts and execute documents without one.

A "company stamp" bought from an office supplier is not the same thing as a common seal. A common seal is a statutory concept. If your company has one, s 123(1) requires it to show the company's name and, where the ACN is not part of the name, the ACN or the ABN (if the last nine digits of the ABN match the ACN in the same order). Using, or authorising the use of, a seal that purports to be the company's common seal but does not comply is a strict liability offence (s 123(3) to (4)).

A rubber stamp with your company details has no statutory status at all. Stamping a document with it does not, by itself, execute anything. Because the seal rules attach only to a "common seal", most SMEs are better off never adopting one and treating any stamp purely as an admin tool.

The second obligation: execute documents with the right signatories

The obligation that matters in practice is not "have a stamp". It is "execute documents properly". Section 127 of the Corporations Act sets out how a company executes documents itself:

• Without a common seal (s 127(1)): a document is executed if it is signed by two directors; or a director and the company secretary; or, for a proprietary company with a sole director, that director alone where they are also the sole secretary or the company has no secretary.
• With a common seal (s 127(2)): the seal is fixed to the document and its fixing is witnessed by the same combinations of directors and secretary. The witnessing can be done by electronic means (s 127(2A)).
• As a deed (s 127(3)): a document takes effect as a deed if it is expressed to be executed as a deed and is executed under s 127(1) or (2). Since the 2022 amendments, a deed executed under s 127(1) needs no witnessing at all and can be signed in electronic form (s 127(3A)). Delivery of the deed is not required (s 127(3B)).
• Other methods are not excluded (s 127(4)): your constitution can set out additional or different execution methods, and s 126 lets an individual with the company's express or implied authority make contracts and execute documents on its behalf. That is how a general manager or delegated officer can sign, but only with real authority behind them.

The signatory rules matter because of what the other side is entitled to assume. If a counterparty can see that a document appears to be signed in accordance with s 127(1), they are entitled to assume it has been duly executed by the company (s 129(5)). That assumption is what makes the other side's lawyer comfortable signing off on a deal. Sign with the wrong combination, for example a single director of a company that has a secretary, and the counterparty cannot make that assumption, and a dispute about whether the company is bound becomes much more likely.

The third obligation: get electronic signing right

Most SME documents are now signed electronically, and the Corporations Act has kept pace. Under s 110A (in Part 1.2AA, added by the 2022 amendments), a person may sign a document electronically if the method of signing identifies the person and indicates their intention, and the method is as reliable as appropriate for the purpose, or is proven in fact to have done so. In plain terms, a platform that captures the signer's identity and keeps an audit trail is more likely to meet the test than a bare email signature block, but a basic electronic signature can still be valid if it is shown to have worked.

Electronic execution applies to deeds as well. Section 127(3A) allows a deed to be executed under s 127(1) in electronic form without witnessing, and the note to s 127 confirms the signing requirement can be satisfied electronically.

The caveats are practical ones. Some documents carry extra formalities that the Corporations Act does not override. Land dealings under state and territory law, documents lodged with particular registries, and deeds required by a counterparty's own jurisdiction (including overseas parties used to seal-based execution) can all have additional requirements. Before final sign-off on a high-value or unusual document, confirm in writing what form of signing the other side will accept.

The fourth obligation: show your name and ACN on public documents

The obligation a stamp most plausibly serves is in s 153 of the Corporations Act, and it does not require a stamp at all. Section 153(1) requires a company to set out its name on all its public documents and negotiable instruments (cheques are the classic example). Where the ACN is not part of the company name, s 153(2) requires the ACN, or the ABN where the last nine digits match, to appear with the name. If the name appears over multiple pages, the ACN or ABN must appear on the first of those pages. Breach is a strict liability offence (s 153(3)).

The Act also requires a public company to display its name at its registered office, and every company to display its name at its places of business that are open to the public (see the note to s 153 and s 144).

A stamp with your name and ACN on it is a convenient way to comply consistently. It cuts typos in a nine-digit ACN and keeps forms uniform. But a document template that automatically prints the name and ACN does the same job with no risk of an out-of-date stamp.

What happens when you get it wrong

The consequences of these obligations are practical rather than headline-grabbing, but they are real:

• A deed may not take effect as a deed: If a document meant to be a deed is not expressed as a deed and executed under s 127, it may fail to bind the company, and the enforceability and limitation position can change.
• The counterparty loses the s 129(5) assumption: If the document was not signed in an s 127 combination, the other party cannot assume due execution, and either side can litigate whether the company is bound.
• An uncontrolled signature or seal can bind you anyway: Section 128(3) lets a counterparty rely on the statutory assumptions even where an officer of the company acted fraudulently or forged a document. The only escape is s 128(4): the assumptions cannot be used by someone who knew or suspected they were incorrect. In practice this means a rogue employee who forges a director-style signature, or uses the seal without authority, can commit the company to a deal the board never approved, unless the other side was on notice.
• Strict liability offences: Missing name or ACN on public documents (s 153(3)) and using a non-compliant common seal (s 123(4)) are strict liability offences. No intention or negligence needs to be shown.

None of this is about the stamp. It is about control over who can make the company's signature mean something.

Compliance checklist

Here is what to check to keep your stamp and signing obligations in order:

• Check for a common seal: Confirm whether your company has adopted one (check your constitution). If it has, make sure the seal shows the name and ACN (or matching ABN) and is stored securely.
• Write down your signatory protocol: Which combination of directors and secretary signs ordinary contracts, and which signs deeds.
• Handle deeds deliberately: For any deed, make sure it is expressed to be executed as a deed and signed in an s 127 combination.
• Choose your e-signing method: Use a method that identifies the signer and records their intention with a reliable audit trail.
• Follow your constitution: If it requires a seal or specific signatories, comply with it.
• Review your templates: Confirm that invoices, quotes, contracts and receipts show the company name and ACN (or ABN) on the first page.
• Control the stamp: Record who may use any stamp or seal, when, and how use is logged.

When a lawyer's help is worth it

Most of this is housekeeping you can do yourself. A commercial lawyer earns their fee in the situations where the rules stop being routine:

• Constitution drafting: If you want execution methods beyond the statutory defaults, or you are setting up multi-director governance, the constitution is where those rules live.
• Deeds for significant transactions: Property deals, guarantees and settlement agreements often carry state-specific formalities that sit on top of s 127.
• Disputes about whether the company is bound: If a document was signed by the wrong person, or a seal was used without authority, the question of whether the assumptions in ss 128 to 129 protect the counterparty is exactly the kind of issue a lawyer should assess early.
• Counterparties demanding seal execution: Overseas parties or legacy institutions sometimes insist on a seal or particular attestation. A lawyer can confirm what is actually required rather than what the other side's checklist assumes.

The mistake that costs more than any missing stamp

The most expensive error in this area is not failing to buy a stamp. It is letting the company's signature circulate without control: the seal itself, or a director's authority to sign under s 127. Because of s 128(3), a company can be bound by a document it never approved, signed by someone who had no authority, where the counterparty relied in good faith. That is a risk no rubber stamp creates and no rubber stamp prevents.

So this week, do the one thing that matters. Write down who can sign for the company, in what combination, and for which documents, and make sure any seal is locked away with a record of its use. If you cannot answer those questions confidently, that is the moment to take the execution clause of your constitution, and your signing habits, to a lawyer before a dispute does it for you.