This page covers formation once you have identified the offer — acceptance, its communication, prescribed methods, and how offers terminate. For the separate question of whether a statement was a true offer at all, see our note on offer vs invitation to treat.
The objective test
Irish contract law does not ask what a party privately intended; it asks how a reasonable person in the other party's position would have understood their words and conduct. The classic statement is Smith v Hughes (1871) LR 6 QB 597 Court of Queen's Bench (E&W): a party who so conducts himself that a reasonable person would believe he was assenting is bound as if he had intended to agree. What matters is intention as communicated to and understood by the other party (The Hannah Blumenthal [1983] 1 All ER 34 Court of Queen's Bench (E&W)). Every rule below is ultimately an application of this test.
What can be accepted: a real offer
An offer is a clear, unambiguous statement of the terms on which the offeror is willing to be bound the moment it is accepted — nothing further is needed from them for a contract to arise. A statement that leaves the maker free to walk away is not an offer. In Hoare v Allied Irish Banks plc [2014] IEHC 221 High Court (Commercial) (IE) a bank's statement that it would show some forbearance was held to be an intimation that it would do its best — not a definite offer capable of acceptance.
Unilateral offers are accepted by performing an act rather than by promising. The foundational case is Carlill v Carbolic Smoke Ball Co [1893] 1 QB 256 Court of Appeal (E&W). Irish courts apply the same idea: an employer's unconditional notice offering half-pay to employees who enlisted was a unilateral offer accepted by joining up (Billings v Arnott & Co (1946) 80 ILTR 50 Ireland), and a signed voluntary-severance offer became binding on the employee's acceptance (Browne v Iarnród Éireann [2014] 2 IR 506 Ireland).
Acceptance must be final, unqualified — and communicated
Acceptance is a final and unequivocal expression of agreement to all the terms of the offer. Two ingredients: the fact of acceptance and its communication. Both were missing in Parkgrange Investments v Shandon Park Mills (HC, 2 May 1991) Binding (IE), where a vendor signed a contract only for tax purposes, kept it with his solicitor and never sent it — no intention to accept and nothing communicated.
Acceptance can be inferred from conduct. In Brogden v Metropolitan Railway (1877) 2 App Cas 666 England & Wales the parties acted for years on an unexecuted draft; ordering and supplying under it accepted its terms.
Acceptance must mirror the offer. Introduce a new term and you make a counter-offer, not an acceptance: in Swan v Miller, Son & Torrance [1919] 1 IR 151 Ireland a purported acceptance that added a £50 annual ground rent was a counter-offer. A counter-offer also destroys the original offer, which cannot afterwards be accepted (Hyde v Wrench (1840) 3 Beav 334 England & Wales). A mere request for information, by contrast, leaves the offer standing (Stevenson, Jacques & Co v McLean (1880) 5 QBD 346 England & Wales).
Silence is (usually) not acceptance
An offeror cannot impose a contract by treating silence as assent. In Felthouse v Bindley (1862) 11 CB (NS) 869 Court of Common Pleas (E&W) (the buyer wrote that if he heard no more he would treat the horse as his) there was no acceptance. Irish law is the same: in Russell & Baird v Hoban [1922] 2 IR 159 Ireland a note deeming silence to be acceptance after three days was ineffective: Ronan LJ held that one party cannot impose such conditions on another. Narrow exceptions exist — for example where both parties agree silence will bind, or where an established course of dealing dispenses with express acceptance. What can look like a further exception — taking the benefit of work that a reasonable person knows is not gratuitous — is better analysed as acceptance by conduct: the offeree's actions, judged objectively, manifest assent. It is the conduct, not the silence, that accepts.
Prescribed methods, and where acceptance takes effect
Where the offeror prescribes a method of acceptance, that method may need to be completed before a contract arises, and the offer can be revoked before it is (Walker v Glass [1979] NI 129 Chancery Division (NI)). As a general rule acceptance is effective on receipt; the well-known postal rule is a narrow exception (acceptance complete on posting where post was contemplated). Because the timing rules for post differ from those for revocation, they are a favourite exam trap — see our dedicated note on the postal rule.
How an offer ends
An offer must still be alive when accepted. It can end by:
- Revocation. An offer may be withdrawn any time before acceptance — even where the offeror promised to keep it open — unless the offeree gave consideration for that promise (an option). Withdrawal is effective only when communicated (Byrne v Van Tienhoven (1880) 5 CPD 344 England & Wales), and notice can come from any reliable source, not just the offeror (Dickinson v Dodds (1876) 2 Ch D 463 Court of Appeal (E&W)). A unilateral offer that has been performed is a different matter: performance is the acceptance, so a purported revocation afterwards is too late. That point is Irish — in Billings v Arnott & Co Ltd (1946) 80 ILTR 50 Ireland Maguire J held acceptance was complete when the employee joined the Defence Forces and told the company, and the company could not then withdraw the offer as against him.
- Rejection or counter-offer (Hyde v Wrench).
- Lapse of time — on expiry of any stated period, or after a reasonable time judged by the subject-matter (Ramsgate Victoria Hotel v Montefiore (1866) LR 1 Ex 109 England & Wales).
- Death — a standing offer is determined once the other party has notice of the death. In In re Whelan, deceased; Dodd v Whelan [1897] 1 IR 575 Ireland a continuing guarantee was held to have been determined on the date the bank first had knowledge of the guarantor’s death.
Knowledge and motive
You cannot accept an offer you do not know exists (R v Clarke (1927) 40 CLR 277 Australia). But once you know of it, your motive for accepting is irrelevant (Williams v Carwardine (1833) 4 B & Ad 621 Court of King's Bench (E&W)).
The full, exam-ready version
Formation I: offer, termination, acceptance, certainty and formalities — with the full case table, worked problems, a decision-tree and a model-answer skeleton.
see the full Contract course →Common questions
When is acceptance effective?
As a general rule, on receipt by the offeror. The postal rule is a narrow exception: where acceptance by post is contemplated, it is complete on posting.
Can silence ever be acceptance?
Generally no — an offeror cannot impose silence as acceptance (Russell & Baird v Hoban; Felthouse v Bindley). Narrow exceptions include an agreed course of dealing or the offeree's own undertaking to speak.
Can an offer be withdrawn after the offeror promised to keep it open?
Yes, unless the offeree gave consideration for that promise (an option). A bare promise to hold an offer open is not binding, and revocation is effective once communicated — from any reliable source (Dickinson v Dodds). The exception is a unilateral offer that has already been performed: performance is the acceptance, and on Billings v Arnott the offer can no longer be withdrawn.
The one-page answer structure, free by email
The answer-structure page, free. A short note too when a case explainer goes up and when an exam is close. No other mail.