A two-page letter answers one question and leaves forty unanswered. A purchase agreement is the document that answers the other forty.
Two companies agree to a deal over lunch: one buys the other's warehouse operation for £2.4 million. Straightforward, both sides say. They exchange a two-page letter confirming price and closing date, shake hands, and instruct their lawyers to "paper it up".
The papering-up takes eleven weeks. Not because the lawyers are slow, but because the two-page letter answered one question and left forty unanswered. Who bears the risk if a forklift fails inspection the week before closing? What happens to the eighteen employees? Does the buyer inherit the dispute with the haulage contractor? Which of the seller's statements about condition can the buyer sue on afterwards, and for how long? What if the buyer's financing falls through?
A purchase agreement is the document that answers those forty questions. Its length is not lawyerly indulgence — it is the price of allocating risk explicitly rather than discovering the allocation in court.
A purchase agreement is a contract setting out the terms on which one party sells and another buys an asset, a business, goods, or property. It records what is being sold, for how much, when ownership and risk transfer, what each party promises about the subject matter, and what happens if those promises turn out to be wrong.
It differs from a purchase order in scope and purpose. A purchase order is a transactional instrument for routine buying — quantity, price, delivery. A purchase agreement is a negotiated document for transactions where the risk allocation matters more than the mechanics.
The buyer acquires specified assets and, usually, specified liabilities. Everything not listed stays with the seller. Buyers generally prefer this structure because it allows them to leave unwanted liabilities behind — though employment protection legislation in many jurisdictions transfers employees automatically regardless of what the agreement says, which regularly surprises first-time buyers.
The trade-off is complexity. Each category of asset may transfer differently: property by deed, contracts by assignment or novation requiring counterparty consent, intellectual property by separate assignment, regulatory licences sometimes not at all.
The buyer acquires the shares in a company, and with them everything the company owns and owes. Cleaner to execute — one transfer rather than dozens — but the buyer inherits the entire history, including liabilities nobody has discovered yet. This is covered in depth in what a share purchase agreement is.
Governed by property-specific law and formality requirements. Almost universally must be in writing, often requires execution as a deed, and involves title investigation, searches, and registration steps that have no equivalent in other sales.
For significant one-off purchases of equipment or inventory, or as a framework for recurring supply. Sale of goods legislation supplies implied terms about quality, description, and fitness for purpose, which the agreement may modify within limits set by consumer and unfair terms law.
Correct legal entities, not trading names. The definitions section is not boilerplate — it is where much of the negotiation actually happens. What counts as "Excluded Liabilities", what falls inside "Business Assets", and what "Material Adverse Change" means are commercial questions dressed as drafting ones.
What is being sold, described precisely enough that a stranger could identify it. Then the price, and critically the mechanism: fixed sum, adjusted at completion against working capital or net debt, deferred, or contingent on future performance through an earn-out. Price adjustment mechanics generate a disproportionate share of post-closing disputes, usually because the accounting policies underlying the calculation were left vague.
Things that must happen before completion is obliged to occur: regulatory clearance, third-party consents, financing, landlord approval, no material adverse change. Each condition needs an owner, a longstop date, and a stated consequence if it is not satisfied.
Statements of fact about the subject matter. The seller warrants title, condition, compliance, absence of undisclosed litigation, accuracy of accounts, and so on. If a warranty proves false, the buyer has a claim.
The negotiation here is rarely about whether to give warranties. It is about their qualification: knowledge qualifiers ("so far as the seller is aware"), materiality thresholds, and the disclosure letter, which carves out specific known issues from warranty protection. A warranty fully disclosed against is a warranty that gives the buyer nothing.
Distinct from warranties. An indemnity is a promise to reimburse a specified loss pound for pound, typically used for known or anticipated risks — an ongoing tax enquiry, a contaminated site, a live dispute. Unlike warranty claims, indemnity claims usually avoid arguments about causation and mitigation.
The seller's protections: a financial cap (often a percentage of price, sometimes the whole price for title warranties), a de minimis threshold so trivial claims cannot be brought, a basket so claims must aggregate before any are payable, and time limits — commonly twelve to twenty-four months for general warranties, longer for tax.
Promises about conduct. Pre-completion, the seller typically agrees to run the business normally and not to take specified actions. Post-completion, covenants commonly include non-compete and non-solicit restrictions, transitional cooperation, and confidentiality.
Where, when, and what each side delivers. A completion checklist attached as a schedule prevents the familiar scene of a closing delayed because nobody brought a board resolution.
In simple sales they happen simultaneously. In most substantial transactions they do not, and the gap between them is a distinct phase with its own rules.
Between signing and completion the parties are bound but the asset has not transferred. Conditions are being satisfied, consents chased, financing drawn. The agreement governs this period through pre-completion covenants and, often, a right to walk away if something material goes wrong. Understanding that a signed agreement is not necessarily an effective one is the same distinction explored in what an executed contract actually means.
The agreement does not stop mattering when the money moves. Warranty claim periods run for months or years. Earn-out calculations depend on how the business is operated post-closing. Restrictive covenants bind the seller. Transitional services obligations continue. Tax covenants may survive for the better part of a decade.
These obligations sit scattered through the agreement and its schedules, expressed in relative terms — "within 20 business days of the Completion Accounts becoming final" — rather than as dates anyone has calendared. The people who negotiated them move on. The agreement becomes a flat PDF nobody can query. Then a claim window closes unnoticed, or an earn-out dispute arises because nobody tracked the operating covenants. Disciplined contract obligation tracking from completion onward is what prevents this, and it is far cheaper than reconstructing the position two years later.
A purchase order is a transactional document — usually an offer to buy specified items at a specified price, used for routine, repeatable purchasing. A purchase agreement is a negotiated contract used where the risk allocation matters: it deals with warranties, indemnities, conditions, liability caps, and what happens if the subject matter is not as described. POs handle volume; purchase agreements handle consequence. Many organisations use both, with POs issued as call-offs under a governing agreement.
Substantively yes — the difference is perspective. The same document may be called a purchase agreement by the buyer and a sale agreement by the seller, and "sale and purchase agreement" is the neutral form common in transactional practice. There is no legal distinction created by the name. What matters is the content: who is selling what, on what terms, with what protections.
In an asset purchase the buyer acquires identified assets and assumes only identified liabilities, leaving the rest with the seller. In a share purchase the buyer acquires the company itself and inherits everything it owns and owes, including unknown liabilities. Buyers generally prefer asset deals for the liability protection; sellers generally prefer share deals for the clean exit and often more favourable tax treatment. Asset deals are more complex to execute because each asset class may transfer by a different mechanism, and employees frequently transfer automatically under employment protection legislation regardless.
Not always, but frequently. Statute of frauds provisions in most jurisdictions require writing for transfers of interests in land, and often for guarantees and agreements that cannot be performed within a year. Beyond those categories, an oral agreement to sell can be binding — but proving its terms later is extremely difficult, and for anything with warranties, conditions, or liability limits the entire value of the document lies in its precision. In practice, anything worth a purchase agreement is worth writing down.
Statements of fact made by one party, usually the seller, about the subject matter of the sale — that they own it, that the accounts are accurate, that there is no undisclosed litigation. If a statement is untrue, the other party has a claim. In common law practice representations and warranties have technically different remedies, with misrepresentation potentially allowing rescission, but commercial agreements usually address this expressly. The commercially significant negotiation is over their qualification: knowledge limits, materiality thresholds, disclosure against them, financial caps, and time limits.
It varies by transaction and jurisdiction, but general commercial warranties commonly run twelve to twenty-four months from completion — long enough to cover at least one full audit cycle, which is when problems typically surface. Tax warranties and covenants usually run considerably longer, often aligned to the relevant statutory assessment period. Title and capacity warranties are frequently unlimited or subject to a much longer period, since a defect in title is fundamental. These periods are commercially negotiated rather than fixed by law.
HERO is built for documents like these — where a defined term used in clause 8.3 was set in clause 1.1 and amended in a side letter, and where getting that chain wrong is expensive. Definitions, cross-references, schedules, and post-completion obligations stay structured and addressable rather than flattening into a PDF. Book a demo and bring your most heavily negotiated agreement.