Unilateral Contracts in New Zealand

If you run a small business, you probably make “deals” all the time without calling them contracts.

A customer sees your offer and acts on it. A supplier hits a performance target and gets a bonus. Someone completes a task you publicly offered to pay for.

These situations often fall into the legal category of a unilateral contract – and getting it right can save you from misunderstandings, disputes, and costly backtracking later.

Below, we’ll break down what a unilateral contract is in New Zealand, practical examples you’ll actually see in business, and simple tips to make your unilateral offers enforceable (and avoid accidentally creating obligations you didn’t mean to).

What Is A Unilateral Contract?

A unilateral contract is a contract where one party makes a promise and the other party accepts that promise by performing an act (rather than by promising something in return).

In plain English: you say, “If you do X, I’ll pay you Y.”

The other person doesn’t need to sign anything or say “I accept” in words. They accept by doing the thing.

Unilateral Contract vs “Normal” (Bilateral) Contracts

Most business contracts are bilateral – both parties exchange promises. For example, “We will deliver products every month, and you will pay within 14 days.”

A unilateral contract is different because only one side makes a promise upfront. The other side isn’t bound to do anything, but if they perform the required act, the party who made the promise may be legally required to follow through.

Do Unilateral Contracts Need To Be In Writing?

Often, unilateral contracts can be formed without a formal written agreement or signature.

That said, “no paperwork” doesn’t mean “no legal risk”. If your offer and the other party’s performance match up, you can still end up with an enforceable contract.

Whether your unilateral contract is enforceable usually comes back to the same fundamentals as any other agreement – offer, acceptance, consideration, and certainty – which we cover in more detail in what makes a contract legally binding.

How Does A Unilateral Contract Work In Practice?

A unilateral contract usually follows a simple pattern:

You make an offer to the world, to a group, or to a specific person (e.g. “We’ll pay a $500 referral fee if you introduce us to a client who signs a 12-month service”).
The other party performs the required act (e.g. they introduce the client, and the client signs).
A contract is formed upon performance (and you may be obligated to pay the referral fee).

This structure is common in small business because it’s quick, flexible, and easy to implement – especially for promotions, incentives, and one-off arrangements.

Why It Matters For Small Businesses

Unilateral contracts can be useful because they:

encourage action (e.g. referrals, early payment, meeting milestones);
reduce negotiation time (you set the terms upfront);
help you control risk by only paying when the outcome is achieved.

But they can also create problems if:

your “offer” is vague or changes halfway through;
more people accept than you expected (and you’re suddenly liable to pay out);
you unintentionally make a binding promise through advertising or messaging.

That’s why it’s worth thinking about unilateral offer wording the same way you’d think about your customer terms or a Service Agreement – clear, consistent, and written to match how you actually operate.

Common Unilateral Contract Examples For NZ Businesses

Here are some of the most common unilateral contract examples we see in everyday business. Even if you don’t label them “contracts”, they can still be treated as legally meaningful promises.

1) Referral Fees And “Bounty” Offers

You might offer:

“We’ll pay you $300 for any referral that becomes a paying customer.”
“$1,000 finder’s fee if you introduce us to a landlord and we secure the lease.”

These can become unilateral contracts once the referral conditions are met. If you don’t want a binding obligation, you need to be careful about wording (for example, making it subject to approval, limits, or a written agreement).

2) Promotions, Discounts, And Public Offers

Retail and eCommerce businesses often run campaigns like:

“Show this code for 20% off.”
“First 50 customers get a free upgrade.”
“Buy one, get one free this weekend.”

Promotional statements can be risky if they’re unclear, misleading, or not honoured. Even if a promotion isn’t a unilateral contract in every scenario, you still need to be careful under consumer law.

In New Zealand, your advertising and representations can trigger obligations under the Fair Trading Act 1986 (misleading and deceptive conduct) and the Consumer Guarantees Act 1993 (consumer rights relating to goods and services).

3) Performance Bonuses And Incentives

Businesses often use unilateral-style incentives such as:

“If you hit $50k sales this month, you’ll get a $2k bonus.”
“If the project is delivered by Friday, there’s a $500 completion bonus.”

These may sit alongside an employment relationship or a contractor relationship, so it’s important the incentive doesn’t conflict with your existing terms.

If you’re setting incentives for staff, it’s usually safer to keep the legal foundations clear in an Employment Contract (or a written policy that’s consistent with it), so the “bonus promise” doesn’t become a surprise entitlement later.

4) Rewards For Completing A Specific Task

Sometimes unilateral offers are made for a specific outcome, such as:

finding and returning a lost item;
reporting a security bug in your software (a “bug bounty”);
providing a lead that results in a signed deal.

These are classic unilateral contract scenarios: performance is the acceptance.

5) Quotes, Estimates, And “If You Accept, We’ll Do It For This Price”

Many small businesses send out quotes that look like: “Here’s the scope and price. If you want to proceed, we can book you in.”

Depending on how it’s written and what happens next, a quote can be treated as an offer capable of acceptance.

This is a common risk area, especially if your quote is missing exclusions, assumptions, expiry dates, or a variation process. If this is relevant to you, it’s worth tightening up your quoting process and understanding is a quotation legally binding.

When Is A Unilateral Contract Enforceable In New Zealand?

In New Zealand, unilateral contracts are generally enforceable if they meet the usual contract law requirements.

Most of the core rules about whether a contract exists (including unilateral contracts) come from judge-made law (case law). Depending on the situation, statutes can also matter - for example, the Contract and Commercial Law Act 2017 applies to a range of contract-related issues (like remedies in some contexts) and consolidates several earlier laws.

For a unilateral contract, the enforceability questions usually focus on the following.

1) Was There A Clear Offer (Not Just “Sales Talk”)?

Your offer needs to be sufficiently clear so that a reasonable person can understand:

what needs to be done to accept (the required act);
who can accept (anyone, a limited group, or a specific person);
what the reward/benefit is; and
any limits, conditions, deadlines, or exclusions.

If the statement is too vague, it may be treated as an invitation to negotiate rather than a binding offer.

2) Was The Offer Accepted By Performance?

In a unilateral contract, acceptance happens when the other party does the act you required.

This is why clarity matters: if your terms don’t define what counts as “completion”, you may end up disputing whether acceptance occurred.

3) Was There Consideration?

Consideration is the “price” of the promise. In unilateral contracts, the consideration is typically the effort or act performed by the person accepting.

Example: if you promise to pay a referral fee, the act of introducing a customer (and meeting your conditions) is the consideration.

4) Are The Terms Certain Enough To Enforce?

If key terms are missing or uncertain (like the scope, timing, or reward), enforceability becomes harder.

This is where many small businesses get caught out: a quick DM, email, or website banner might feel “informal”, but if it’s specific enough, it can still be enforceable.

5) Did Anyone Rely On A Misleading Statement?

Even where there’s a contract argument, you also need to watch for claims based on misleading conduct or misrepresentation.

For example, if you promise a reward, then change the criteria after someone has already acted, you can create real legal exposure (contractual and otherwise).

This risk comes up a lot in marketing and sales, so it’s worth being familiar with what is misrepresentation and how it can lead to disputes.

6) Is It Actually Intended To Be Binding (Or Is It Non-Binding)?

Sometimes you want to float an idea without creating a legal obligation. That’s fine – but you need to communicate it properly.

For example, if you say “We may offer a bonus at our discretion” or “Subject to contract”, that can help show it isn’t intended to be binding yet.

If you commonly use “non-binding” language in negotiations, it’s worth understanding what is a non-binding contract and when that wording does (and doesn’t) protect you.

How Can You Draft A Unilateral Contract Offer That Protects Your Business?

You don’t always need a long-form agreement to make a unilateral contract workable. But you do need to be intentional.

Here are practical enforceability tips that help you avoid disputes and keep your offers commercially sensible.

1) Put The Offer In Writing (Even If It’s Short)

A unilateral contract can be created verbally, but written terms make it much easier to prove:

what was offered;
when it was offered;
what conditions applied; and
whether the conditions were met.

Writing can be an email, a webpage, a printed flyer, or a one-page terms document. The key is clarity and record-keeping.

2) Define Exactly What Counts As “Acceptance”

Be specific about the act that forms acceptance. For example:

Is it enough to “refer” someone, or does the person need to sign and pay?
Does the reward apply to the “first sale” only, or renewals too?
Does the act need to be done by a deadline?

If you can, include objective criteria (dates, payment received, signed contract, delivery confirmation) rather than subjective criteria (“good lead”, “successful project”).

3) Include Limits, Caps, And Eligibility Rules

Many disputes happen because an offer is open-ended.

Consider including:

eligibility (e.g. “not available to existing customers/clients”);
caps (e.g. “limited to the first 10 valid referrals”);
one per person rules;
geographic limits (e.g. Auckland only);
expiry dates and timeframes;
verification requirements (e.g. “referrer must be the first person to introduce the client”).

4) Be Careful About Changing Or Withdrawing The Offer

It’s common for businesses to tweak promotions or incentives on the fly. The tricky part is that someone may already be in the process of performing the act required for acceptance.

As a general rule, you can usually withdraw a unilateral offer before it has been accepted - but once someone has started performing in reliance on the offer, trying to revoke or change it can become legally risky (and may not be effective for that person). If you want flexibility, it’s best to be clear upfront about when changes take effect and how you’ll treat people already in progress.

If you want the ability to withdraw or vary an offer, you should think about:

how you’ll give notice (website update, email, written message);
whether changes apply prospectively only; and
how you’ll treat people already part-way through performance.

Getting this wrong is how “marketing offers” turn into disputes that take time, money, and customer trust to resolve.

5) Make Sure Your Offer Doesn’t Conflict With Other Contracts

If you’re making unilateral promises in a business that already runs on contracts, check for mismatches. For example:

A sales commission “promise” that doesn’t match the commission clause in your employment documents;
A public “money-back guarantee” that isn’t reflected in your refunds policy or customer terms;
A supplier bonus offer that conflicts with your existing supply arrangements.

If you want confidentiality around the arrangement (for example, a one-off reward for a specific referrer or introducer), you may also want a simple Non-Disclosure Agreement in place before you share sensitive details.

6) Use “Subject To” Language When You Need Approval

Sometimes you want to motivate action, but you still need internal approvals (e.g. board sign-off, finance approval, compliance checks).

In those cases, it may be more appropriate to say the offer is:

“subject to written confirmation”,
“subject to eligibility checks”, or
“subject to contract”.

Just be careful: “subject to” language should be genuine. If you present something as a sure thing, and then later try to treat it as discretionary, you can create enforceability problems.

7) Think About Evidence (If There’s A Dispute)

If the deal goes sideways, you’ll want to show what happened and when. As a practical checklist, keep:

dated screenshots of offers you posted publicly (website, social media);
email threads confirming the terms;
records showing the conditions were (or were not) met;
invoices, payments, and delivery confirmations.

And remember: even where you do have a signed document, enforceability still depends on the content and circumstances. If this comes up in your business, it’s helpful to understand what makes a signed document legally binding (because a signature is important, but it’s not the whole story).

Key Takeaways

A unilateral contract is where one party makes a promise and the other party accepts by performing an act, not by exchanging a promise.
Common unilateral contract examples for small businesses include referral fees, promotions, performance bonuses, and “reward for outcome” offers.
Unilateral contracts can be enforceable in New Zealand if there is a clear offer, acceptance by performance, consideration, and sufficiently certain terms (and the arrangement isn’t misleading).
Marketing and incentive offers should be drafted carefully to avoid issues under the Fair Trading Act 1986 and other consumer law obligations.
You can protect your business by putting the offer in writing, defining what counts as acceptance, setting limits and expiry dates, and keeping records of what was offered and what was done.
If you need flexibility, use careful “subject to approval” wording (and make sure your internal practices match what you say publicly).

If you’d like help documenting an incentive, promotion, referral arrangement, or contract terms so your business is protected from day one, you can reach us at 0800 002 184 or team@sprintlaw.co.nz for a free, no-obligations chat.

Unilateral Contracts In New Zealand: Meaning, Examples & Enforceability