Reasonable Endeavours vs Best Endeavours In UK Contracts

If you’re negotiating a new deal, chances are a draft contract will ask you to use “reasonable endeavours” or “best endeavours” to do something. It sounds harmless, but the phrase you pick can change how much time, cost and risk you’re committing to.

In UK contracts, endeavours clauses are common - in supply terms, distribution agreements, SLAs and even investment paperwork. Understanding the difference between reasonable endeavours vs best endeavours can save you from over‑promising, disputes and unexpected expense.

In this guide, we break down what each obligation really requires under English law, how courts assess compliance, and practical drafting tips so you can set expectations clearly and protect your position from day one.

What Do “Endeavours” Clauses Mean Under UK Law?

At a high level, an “endeavours” clause asks a party to try to achieve a specified outcome, rather than guaranteeing that outcome. You’re contracting to take certain efforts, not to deliver a result at all costs.

These clauses often appear when the outcome isn’t fully within one party’s control - for example, seeking a licence from a regulator, persuading a landlord to consent, obtaining third-party approvals, or hitting a non-critical delivery timeline despite supply chain constraints.

Under English contract law, the exact words matter. Different formulations have developed through case law and market practice. The most common are:

• Reasonable endeavours - a balanced obligation to take steps a reasonable business would take in the circumstances.
• Best endeavours - a more onerous obligation to take all reasonable steps to achieve the goal, potentially at significant effort and cost.
• All reasonable endeavours - usually seen as sitting between the two, but its effect depends heavily on drafting and context.

Because endeavours obligations are about effort rather than absolute results, they should be read alongside your other protections, like a clearly drafted Limitation of Liability, any Service Level Agreement terms, and force majeure provisions. These work together to allocate risk sensibly.

Reasonable Endeavours vs Best Endeavours: The Practical Differences

There’s no single statutory definition for these clauses, but courts and commercial practice give us a reliable guide. Here’s how they differ in plain English.

Reasonable Endeavours

This is the lighter touch promise. It generally requires you to:

• Take one or more reasonable courses of action to try to achieve the objective.
• Balance the obligation against your own commercial interests - you’re not expected to act against them.
• Incur some cost and time if sensible, but not open-ended or disproportionate expense.
• Document your efforts (emails, calls, applications) to show you tried.

Think of it as “do the sensible things a prudent business would do, and stop before it becomes unreasonable.”

Best Endeavours

This is notably more demanding. It’s often interpreted as requiring you to:

• Take all reasonable steps to achieve the objective, even where efforts are extensive.
• Explore multiple avenues, persist, and follow up - not just one reasonable attempt.
• Spend money and commit resources, potentially including working overtime or engaging third parties, where proportionate to the contract’s value and purpose.
• Consider some sacrifice of commercial interests, unless this would be ruinous or clearly unreasonable.

Put differently, “best endeavours” asks you to push hard and keep going until you can fairly say nothing more reasonable could be done.

All Reasonable Endeavours

Many drafters use this as a compromise. In practice, “all reasonable endeavours” often tracks close to best endeavours, particularly if the clause requires prioritising the objective over your own commercial interests. But it can be negotiated so it’s closer to reasonable endeavours if paired with smart qualifiers (for example, excluding a duty to litigate or to spend above a cap).

Why the Wording Matters

• Cost exposure: Best endeavours can mean significant spend. Reasonable endeavours is more controlled.
• Operational burden: Best endeavours may require multiple attempts, escalation and management attention.
• Dispute risk: Vague endeavours wording increases the chance of arguments about whether you “tried hard enough.”

To reduce ambiguity, pair endeavours wording with concrete parameters. We cover drafting tips below.

How Do Courts Assess Whether You Used The Required Endeavours?

Courts look at the clause in its commercial context. There’s no tick‑box test, but common factors include:

• Contract purpose and value: The bigger the deal or the more central the objective, the more effort expected.
• Available routes: Did you explore all sensible pathways, not just the easiest one?
• Cost vs benefit: Was the extra spend or disruption justified relative to the contract’s stakes?
• Market practice: What would a reasonable, prudent business in your sector do?
• Evidence of effort: Paper trails matter - applications lodged, follow‑ups made, alternative options explored, stakeholders engaged.
• Contract constraints: Any express limits (e.g., cost caps, timeframes, “no litigation required”) will be enforced.

Importantly, an endeavours obligation is not a guarantee. If you can show you took the steps the clause requires and the outcome still wasn’t achieved, you’ll usually have complied.

The flip side is that vague drafting can invite disagreement. If you want to avoid a “he said, she said” about efforts, specify the expected steps, timeframes, and spend tolerances up front, and ensure your contra proferentem risk is minimal by drafting clearly.

Which Endeavours Obligation Should You Use In Your Contracts?

The right choice depends on the objective, the risks, and your leverage. Here are common scenarios and how SMEs typically approach them.

Third-Party Consents Or Approvals

Where you need a regulator, landlord, supplier or insurer to say “yes,” use reasonable endeavours unless the consent is mission‑critical and delay would defeat the deal. Consider adding specifics like “submit complete application within 10 business days” and “provide further information reasonably requested.”

Supply Chain Or Logistics

For delivery dates subject to global supply constraints, reasonable endeavours is common. If a customer insists on best endeavours, push for carve‑outs around events beyond your control and ensure you have a sensible Limitation of Liability and force majeure.

Service Levels And Uptime

In technology and managed services, hard targets belong in an SLA, supported by service credits. The endeavours obligation (often “all reasonable endeavours”) then applies to restoration efforts. Be precise about response times and escalation to avoid fuzzy standards; a tailored Service Level Agreement is the right tool here.

Exclusivity And Non-Solicitation

If you’re agreeing to “use best endeavours to promote” a partner’s products during an exclusive period, this can become onerous. Consider reasonable endeavours plus measurable activities (campaigns, meetings, training) rather than open‑ended obligations, and watch for onerous terms that quietly expand your workload.

Financing Or Investment Milestones

Investment documents sometimes require founders to use all reasonable endeavours to hit milestones. Push for clarity on what counts (e.g., “launch MVP” defined by features) and avoid committing to outcomes outside your control. If you’re still at a preliminary stage, consider a lighter Heads of Agreement or Memorandum of Understanding before locking into heavy obligations.

Drafting Tips: Make Endeavours Clauses Clear And Commercial

Endeavours wording doesn’t have to be vague. A few edits can turn a fuzzy promise into a practical standard everyone can live with.

1) Name The Objective Precisely

Vague: “use best endeavours to obtain approvals.” Better: “use reasonable endeavours to obtain the landlord’s written consent to the assignment of the lease (as required by clause X) and to satisfy Conditions A and B.” Precision reduces arguments.

2) Add Objective Steps

Spell out the minimum actions expected. For example:

• Submit a complete application within 10 business days.
• Provide reasonable further information within five business days of request.
• Escalate to a senior contact if no response within 15 business days.
• Engage an alternative supplier if the first declines on reasonable terms.

The more concrete the steps, the easier it is to show compliance.

3) Include Sensible Limits

Qualify the obligation so it aligns with your risk appetite. Typical limits include:

• “No duty to commence litigation, arbitration, or pay any fee to expedite processing.”
• “No obligation to incur costs exceeding £ in aggregate in performing this clause.”
• “Subject to force majeure and third‑party actions outside the party’s control.”
• “No requirement to accept terms that are commercially unreasonable.”

Cost caps are particularly useful where best endeavours is unavoidable.

4) Align With Your Liability And Remedies

Endeavours obligations should sit comfortably with your liability structure. If a missed objective could trigger damages, make sure your examples of carve‑outs and caps are carefully set. If the main remedy should be an extension or service credit, put that in the SLA and make monetary claims a last resort.

5) Avoid Conflicting Language Elsewhere

Watch out for “for the avoidance of doubt” or a roaming notwithstanding clause that unintentionally upgrades your obligation. Cross‑check the entire agreement so definitions, timelines and responsibilities all point in the same direction.

6) Make Renewal And Change Processes Work

If performance evolves over time, a simple process to update obligations helps. Use a contract amendment or change control mechanism so both parties can adjust steps, caps or timelines without re‑negotiating the whole deal.

7) Keep Records As You Perform

Finally, build a paper trail. If you’re later asked to prove you used the required endeavours, email records, tickets, applications, logs and meeting notes are your friends. Good housekeeping now can resolve a dispute before it begins.

Common Places You’ll See Endeavours Clauses (And What To Watch)

You’ll encounter endeavours language across many commercial agreements. Here’s where it typically appears - and how to keep it balanced.

Supply Agreements

Manufacturers and distributors often promise to use reasonable or all reasonable endeavours to meet forecasts, secure raw materials or onboard new customers. Balance this with realistic lead times and firm exclusions for events outside your control. It’s also smart to split “firm orders” from “non‑binding forecasts” within your Supply Agreement so endeavours attach to the right obligations.

Technology And Managed Services

Service providers frequently commit to use all reasonable endeavours to restore services, meet response times or deliver enhancements. Treat SLAs and endeavours clauses as a package: align priorities, escalation paths and service credits, and make sure the liability cap aligns with the service value.

Property And Leasing

Sale and lease contracts often require parties to use reasonable endeavours to obtain consents, rectify minor issues or complete searches promptly. Keep the obligations time‑boxed and make it clear nobody has to go to court or pay third‑party premiums unless agreed.

Partnerships, Distribution And Exclusivity

“Best endeavours to promote” can be a trap if it lacks substance. Replace it with specific activities (quarterly campaigns, minimum training sessions, agreed pipeline reporting) so you’re not judged against a vague, high bar. If growth targets are included, make them joint goals rather than unilateral obligations.

Corporate And Investment Transactions

Share sale, subscription and option agreements often include endeavours to satisfy conditions precedent, transfer consents or complete post‑completion steps. Where multiple parties must cooperate, spell out who does what and by when, and consider a coordination schedule. If a condition might fail despite efforts, include a clear termination or long‑stop mechanism.

Pre-Contract Documents

Even early documents can include endeavours obligations. If you’re not ready for that, keep preliminary paperwork non‑binding or light‑touch using a Heads of Agreement or an appropriately worded Memorandum of Understanding, and reserve heavier commitments for the final contract.

Getting The Draft Right: Practical Process For SMEs

Major companies have in‑house legal teams to refine this wording. As a small business, you can still negotiate strong, fair clauses by following a simple process.

Step 1: Map The Real-World Task

List what you’ll actually need to do to achieve the objective: applications, approvals, meetings, follow‑ups, procurement. Use that list to shape the clause’s steps, timeframes and sensible limits.

Step 2: Pick The Right Standard

Default to reasonable endeavours unless there’s a good reason to go higher. If best endeavours is non‑negotiable, add cost caps, time limits, exclusions (no litigation) and a clear long‑stop date to prevent “forever” obligations.

Step 3: Align With Risk Allocation

Make sure your endeavours promises sit alongside a clear Limitation of Liability and appropriate remedies. Don’t let a heavy endeavours clause pair with uncapped exposure.

Step 4: Keep The Contract Coherent

Cross‑check definitions, timelines and responsibilities for conflicts. Watch for stray language that overrides your careful drafting - like a catch‑all “notwithstanding” sentence elsewhere.

Step 5: Get A Fresh Set Of Eyes

Even if you’re comfortable with the commercial terms, a quick Contract Review can spot hidden risks, suggest tighter language, and ensure your protections work together. If you’re commissioning a new agreement, consider engaging Contract Drafting support so the whole document is purpose‑built for your business.

FAQs: Quick Answers To Common Endeavours Questions

Is “Best Endeavours” A Guarantee?

No, but it is closer to a results‑focused promise than reasonable endeavours. You still aren’t guaranteeing success, but you are committing to do everything reasonably possible to get there, including spending money and trying multiple avenues.

Can We Just Say “All Reasonable Endeavours” And Move On?

Be careful. Depending on context, “all reasonable endeavours” can behave like best endeavours. If you want a middle ground, specify the steps to be taken and include sensible limits (time, cost, no litigation). Precision matters more than the label.

What Happens If We Fail Despite Trying?

If you’ve satisfied the endeavours obligation, you’re usually not in breach. That’s why record‑keeping is important. Also ensure the contract’s remedies reflect the commercial reality - for example, extending time for performance or applying service credits rather than damages in the first instance.

Can We Change The Obligation After Signing?

Yes - contracts can be varied by written agreement. Use a short‑form change control or an amendment so any new steps, caps or timelines are crystal clear and properly authorised.

Does Good Faith Affect Endeavours?

English law doesn’t impose a general duty of good faith in all contracts, but courts may read reasonableness and cooperation into endeavours clauses. It’s safer to draft your cooperation duties expressly rather than rely on implied concepts.

Key Takeaways

• “Reasonable endeavours” is a balanced obligation to take sensible steps; “best endeavours” is a heavier commitment to pursue all reasonable avenues, potentially at significant cost and effort.
• Choose the standard that fits the objective and risk. If best endeavours is required, add clear limits such as cost caps, timeframes and exclusions (e.g., no duty to litigate).
• Draft with precision: name the specific outcome, list required steps, set timelines, and align remedies and caps using a coherent Limitation of Liability and SLA structure.
• Keep the contract consistent - avoid conflicting wording elsewhere (including any catch‑all notwithstanding clause) that could accidentally raise the bar.
• Expectations evolve. Build in a clear change process and use an amendment if you need to adjust steps, caps or timeframes later.
• When in doubt, get a quick sense‑check. A targeted Contract Review or bespoke Contract Drafting can ensure your endeavours clause works with the rest of your agreement.

If you’d like help choosing the right endeavours standard or drafting a balanced clause, you can reach us at 08081347754 or team@sprintlaw.co.uk for a free, no‑obligations chat.