Contract By Conduct In The UK: Risks And How To Protect Your Company

You don’t always need a signed document to end up in a legally binding agreement. In UK law, a contract can be formed by what you and the other party do - not just what’s written down. That’s a “contract by conduct”.

For small businesses, this can be both helpful and risky. Helpful when you’ve delivered work and want to be paid. Risky when you’ve accidentally accepted someone else’s unfavourable terms by going ahead.

In this guide, we’ll explain how contracts by conduct are formed, common business situations where they arise, the traps to avoid, and how to set up your processes so you’re protected from day one.

What Is A Contract By Conduct Under UK Law?

A “contract by conduct” (also described as formation by conduct or implied by conduct) is where a legally binding contract arises from the parties’ actions rather than a signed document. In practical terms, a court will look at what actually happened and decide whether your behaviour shows agreement to clear terms with an intention to be legally bound.

The same basic ingredients of any binding contract still apply - offer, acceptance, consideration (value exchanged), intention to create legal relations, and certainty of terms. The difference is that acceptance (and sometimes the offer) is shown by actions rather than signatures or formal words.

Common examples include:

• You place a repeat order with a supplier and they deliver. You pay their invoice - even if you never signed their terms, your conduct can indicate a contract on those terms (or yours, depending on the facts).
• A service provider starts work after you email “go ahead” and you accept the benefit. That conduct can evidence a contract for the scope and fee discussed.
• Customers buy online from your checkout. Their click and payment (plus your published terms) form a contract without any wet ink signature.

If you’re fuzzy on the fundamentals, it’s worth brushing up on what makes a contract legally binding in the UK. It all still applies to contracts by conduct.

When Do Courts Find A Contract By Conduct?

Courts look at the full picture. Here are the key signposts they use to decide whether you’ve entered into a contract by conduct.

Acceptance By Conduct

Acceptance can be demonstrated by actions that are only explicable by agreement - for example, shipping goods after receiving a purchase order with stated terms, or starting work after a fee proposal. If the parties behave as though a deal is done, a court can conclude a binding contract exists even if the formal agreement was never signed.

Course Of Dealing And Custom

Where you’ve traded on certain terms repeatedly, a “course of dealing” may incorporate those terms into later transactions by default. Likewise, a consistent workplace or industry habit can become contractual rights or obligations over time. For employment and operational practices, this overlaps with “custom and practice” - something you can’t ignore as a business owner. See how custom and practice can become contractual if behaviours are consistent, known, and expected.

“Battle Of The Forms”

You send a purchase order with your T&Cs. The supplier acknowledges with their own T&Cs. Who wins? UK courts often apply the “last shot” rule - the last set of terms sent and not objected to before performance may govern, especially if performance then follows. Clear processes (and explicit acceptance) help avoid being stuck with unfavourable terms simply because they were the last email in the chain.

Silence Is Generally Not Acceptance

Silence alone rarely equals acceptance. However, if your silence is combined with conduct that amounts to acceptance (e.g. you take delivery, use the goods, or pay the invoice), acceptance by conduct can be found.

Oral Agreements Versus Conduct

Contracts can be formed orally, by conduct, or both. Many business owners are surprised to learn that oral contracts can be binding - and your follow-on conduct (like performing or paying) often provides the evidence that makes them enforceable.

Real-World Scenarios Where You Might Create A Contract By Conduct

These are everyday situations where small businesses unwittingly enter into contracts by conduct - or can rely on conduct to enforce a deal in their favour.

1) Starting Work Before A Contract Is Signed

It’s common to kick off work after a great call or a “looks good” email, intending to “sort paperwork later”. If the client accepts the output, your performance and their acceptance can establish a contract by conduct - but the terms might be up for debate if you haven’t nailed down scope, fees, IP ownership, and liability caps in writing.

2) Repeat Orders With A Supplier

After months of smooth trading, you and a supplier may each assume your own T&Cs apply. If there’s a dispute (late delivery, quality issues, price changes), the court may look at the course of dealing to decide which terms govern. If their last invoice or acknowledgment included a liability exclusion you never spotted, you could be stuck with it.

3) Accepting a Quote By Acting On It

Even if you don’t sign the quote, placing an order, paying a deposit, or accepting delivery may show acceptance of the quoted terms. The same goes for a service scope: if you engage and accept the benefit, you likely accepted the key terms.

4) Website Sales And Clickwrap

When customers purchase via your site, the act of ticking a box and paying typically creates a contract. The risk sits with you if your online terms are missing or unclear. Make sure your checkout flow clearly surfaces your Terms of Sale so they’re incorporated into the contract.

5) Employee Perks Or Practices That Become Contractual

Offering an informal benefit (e.g. extra days off, regular bonuses, flexible hours) consistently for a long time can turn that practice into a contractual term. That’s the power of conduct and it’s why you should keep your policies clear and consistent - and document changes carefully to avoid unintended obligations. Here’s more on custom and practice becoming contractual.

What Are The Risks Of Contracts By Conduct For Small Businesses?

Contracts by conduct can be useful - but the biggest risks are uncertainty and being stuck with someone else’s terms. Key pitfalls include:

• Unclear scope and deliverables, leading to scope creep and disputes over what’s included.
• No written fee or payment schedule, making it harder to chase late invoices or interest.
• Unfavourable liability positions if the other party’s T&Cs slip in (e.g. exclusions, caps, indemnities).
• IP ownership ambiguity - who owns designs, code, or content if it’s not set out?
• Jurisdiction and governing law surprises - being dragged into proceedings in another country or forum.
• Privacy risks if you collect data without a published Privacy Policy, potentially breaching the UK GDPR and Data Protection Act 2018.
• Employment and HR obligations being created informally through repeated behaviour.

The effect is the same: greater legal risk, reduced bargaining power, and more time and cost resolving disputes.

How To Avoid Unintended Contracts By Conduct (And Make The Right Ones Stick)

You can’t eliminate all risk - but you can design simple processes that control when and how contracts are formed. Here’s a practical playbook.

1) Make Your Terms Impossible To Miss

Publish and consistently use your T&Cs so they’re incorporated into every transaction. For product businesses, that means crystal-clear Terms of Sale surfaced at checkout, on invoices, and on order confirmations. For service work, issue a concise Service Agreement before work starts and make acceptance explicit.

2) Use “Subject To Contract” And “No Work Until Signed” Rules

If you’re negotiating, label communications “subject to contract” and train your team not to start work or accept delivery until the contract is executed. Where that’s not realistic, at least get an email expressly accepting your specific terms before any performance.

3) Control The Battle Of The Forms

Standardise how you respond to the other side’s T&Cs. If they send terms, reply saying you do not accept theirs and that any work proceeds under your attached terms only - then seek written confirmation. Keep a clean audit trail.

4) Build An Evidence Trail

Save quotes, emails, POs, delivery notes, and meeting notes. If a dispute pops up, these records help prove what was agreed and how the contract was formed (including by conduct).

5) Limit Your Liability

Strong, fair caps and exclusions can be the difference between a manageable issue and a business-threatening claim. Review examples of good risk language when drafting by looking at common limitation of liability clauses and ensure your own clauses are tailored to your services.

6) Keep Your Online Legal Pack Up To Date

If you sell or collect data online, ensure your Terms of Sale, Website Terms of Use, and Privacy Policy are current and easily accessible. That way, the contract formed at checkout is on your terms and compliant with consumer and privacy law.

7) Train Your Team

Make sure staff understand that everyday actions - confirming an order, accepting delivery, starting work - can create binding contracts. Simple playbooks and template emails go a long way.

How To Rely On A Contract By Conduct When You Need To Get Paid

Sometimes you want to enforce a contract that wasn’t fully signed. If you’ve delivered work and the client has benefited, acceptance by conduct can help you claim the agreed price or a reasonable sum.

Gather The Right Evidence

Pull together a clear timeline showing what was offered, what was accepted, and what happened next:

• Initial quote, proposal, or scope email.
• Client’s “go ahead” or instruction to proceed (including implied go-ahead, like providing access or assets).
• Records of work performed, delivery, or goods accepted.
• Invoices issued and any part-payments made.
• Any earlier dealings establishing a course of dealing or standard terms.

Courts and tribunals place weight on contemporaneous records. If it ends up in a dispute, a tidy bundle often makes all the difference.

Frame Your Claim Clearly

Your aim is to show there was a contract (even if not signed) with clear terms on price and deliverables, or that you’re entitled to payment for work done on a “reasonable value” basis if price was not fixed. While you should tailor your approach to the facts, the principle is consistent: your conduct and the other party’s acceptance of benefit point to a binding agreement.

Use A Professional, Firm Approach

Start with a polite but firm demand letter summarising the history, what’s owed, and the deadline for payment. Then consider the appropriate forum for enforcement if needed. Getting advice early helps you choose the most efficient route and keep costs in check.

Key Legal Concepts To Keep In Mind

Here are core areas that often intersect with contracts by conduct in small business life.

Consumer Law And Fairness

If you sell to consumers, the Consumer Rights Act 2015 implies terms into contracts about quality, fitness for purpose, and remedies. Even if your T&Cs are incorporated by conduct, they can’t remove statutory rights or include unfair terms. Ensure your sales processes reflect those obligations.

Data And Privacy

If your contract by conduct arises online, you’re likely collecting personal data. The UK GDPR and Data Protection Act 2018 require transparency and lawful processing, which is why a robust, accessible Privacy Policy matters. Consent to marketing must meet specific rules (including “soft opt-in” conditions).

Employment And “Custom And Practice”

Repeated behaviours in your workplace can evolve into contractual terms via conduct. That can include bonuses, enhanced holiday, or flexible arrangements. If you need to change those practices, consult properly and document the change to avoid disputes about implied obligations.

Dispute Prevention Through Documentation

Nothing beats a clear, signed agreement. Where that’s not practical (e.g. low-value orders), ensure your standard documentation is consistent and routinely referenced. Use short-form order forms or checklists that capture the essentials and refer back to your terms. Good housekeeping now reduces ambiguity later.

Essential Documents That Reduce Conduct Risk

To control how and when contracts form - and on whose terms - have these foundations in place:

• Terms of Sale to govern product sales, delivery, returns, and liability.
• Service Agreement covering scope, timelines, fees, IP, confidentiality, and liability caps.
• Website Terms of Use and a checkout flow that clearly surfaces your legal terms before purchase.
• An up-to-date Privacy Policy covering data collection and use.
• Purchase Order or Supplier Terms that you issue when buying, so the supplier isn’t “last shot” by default.
• Internal policy and training so staff don’t accept other parties’ terms inadvertently.

If you do all of the above, a contract by conduct will most likely be a contract on your terms.

FAQs: Quick Answers About Contract By Conduct

Is A Contract By Conduct Enforceable Without A Signature?

Yes - provided the usual elements of contract exist and the parties’ conduct shows agreement to clear terms with an intention to be bound. The evidential question is: what did the parties do?

Can I Be Stuck With A Supplier’s T&Cs If I Never Signed Them?

Potentially. If you proceed after receiving their terms and the circumstances point to acceptance (especially if theirs was the “last shot” before performance), a court may find those terms apply. Guard against this with clear processes and consistent use of your own T&Cs.

What If We Agreed On The Phone And Then Performed?

An oral agreement can be binding, and the following conduct often proves it. If you rely on oral agreements regularly, put a lightweight confirmation step in place so there’s a paper trail.

Does “Subject To Contract” Protect Me?

It helps, but it’s not bulletproof if your overall behaviour contradicts it (e.g. you label emails “subject to contract” but then perform the work and take payment). Use the label - and back it up with process discipline.

Key Takeaways

• A contract by conduct is formed when your actions show agreement to clear terms - even without a signature. Courts look at what you did, not just what you wrote.
• The biggest risks are uncertainty and being stuck with the other party’s terms in a “battle of the forms”. Put processes in place so your terms govern by default.
• Publish and consistently use your legal pack - Terms of Sale, Service Agreement, Website Terms, and a Privacy Policy - so contracts formed online or by conduct incorporate your positions.
• Train your team: accepting delivery, starting work, or paying invoices can create binding contracts. Use “subject to contract” and don’t perform until terms are agreed.
• Limit your exposure with clear risk clauses. Review and tailor your liability caps and exclusions - see common limitation of liability clauses - so a conduct-formed contract still protects you.
• When you need to enforce a deal formed by conduct, assemble a clean evidence trail of the offer, acceptance, performance, and payment history to support your claim.

If you’d like help tightening your terms, setting up safe processes, or resolving a “contract by conduct” dispute, you can reach us at 08081347754 or team@sprintlaw.co.uk for a free, no-obligations chat.