What it means
In a bilateral contract, parties exchange promises to perform, while in the classic unilateral example one person offers a reward and another is free to decide whether to do the requested act. Nobody becomes obliged to search merely because the offer exists.
The offer must be clear enough to identify what performance qualifies and what the promising party will provide, since a vague advertisement may not have the same effect as a specific promise to pay for a defined result. A reward offer could say payment follows the return of a named item to a specified location by a certain date.
The business should keep the offer and its dates and define how multiple contributors qualify. Legal rules on when acceptance occurs and whether an offer may be withdrawn after someone starts performance vary by jurisdiction, and US contract summaries often describe protection for a person who began the invited act, but this is not a universal rule.
Do not assume an offer may be revoked freely until the final step or that it is irrevocable from first contact. Other applicable rules can alter the analysis.
Businesses may use performance-based offers in referral programmes, contests or bounties, though not every sales bonus or promotional campaign automatically has the same legal form. Define eligibility and the evidence of completion.
For a referral, say whether a lead, a signed contract or a paid invoice triggers a reward, and state how existing prospects and duplicate introductions qualify. A spending cap can reduce budget exposure, but it must be communicated fairly before participants act.
The business should not write a cap only into an internal forecast while the public promise remains unlimited, and it should stop advertising once a cap is reached. Avoid retroactive rule changes, and check the published version and law before ending an offer while work is underway.
Review legal exposure and likely participation before launch. For managers, the practical lesson is to state the result, reward, time, limits and process plainly, and local legal review is sensible when the offer is public or regulated.
In practice
Real-world examples.
Example
A company advertises a $1,000 reward for information leading to the return of a stolen van. Someone provides the information that locates the vehicle and is entitled to the reward. The company cannot add new conditions after the information has been given.
Example
A business offers any salesperson who signs 20 new clients this quarter a $10,000 bonus. Staff do not have to accept, but those who hit the target have earned it. The sales director publishes the definition of a signed client so that disputes are rare.
Example
A retailer promises a free gift to customers who spend over $500 in one visit. A customer who does so can claim the gift at the till. The retailer states the end date and any stock limit on the same poster so the promise is not open-ended.
Formula
Calculation
A unilateral contract has no universal financial formula. An illustrative budget check is Expected reward cost = Reward per qualifying result x Expected qualifying results.
Worked example. An invented firm proposes a $2,000 referral reward and estimates 25 qualifying customers. The expected expense is $2,000 x 25 = $50,000 before administration and any taxes.
If a clearly disclosed maximum of 40 rewards is valid and applies to the campaign, the simple maximum reward expense is $2,000 x 40 = $80,000. Whether that limit is enforceable and when rewards become due are legal questions, not results of the multiplication.Case study
Seen in the real world.
This illustrative and entirely fictional example follows Bright Solar, an invented installer. It posts a $3,000 reward for introducing a new customer but leaves "new" undefined and states no expiry or limit. The campaign spreads through a local group, and Bright Solar receives 140 referrals and claims from several people who named the same customer. It cannot solve the problem merely by declaring a new cap after introductions have happened. The firm checks the published wording, evidence and applicable law before deciding claims.
In this invented outcome it honours qualifying rewards and separately works through disputed duplicate introductions. The total possible cost, 140 x $3,000 = $420,000, illustrates why a forecast was not a limit. For the next programme, Bright Solar specifies what counts as a qualifying paid customer, how duplicate referrals are handled, the offer period and a clearly published cap. It records the version visible when each person acted. The legal outcome depends on the facts.
Watch out
Common mistakes.
- Assuming a public promotional promise cannot be binding because nobody signed a paper contract.
- Trying to add limits after people acted on an earlier, broader offer.
- Treating US examples of revocation and partial performance as universal law.
Questions
People also ask.
What is the difference between unilateral and bilateral contracts?
A unilateral offer invites acceptance through a defined act. A bilateral contract involves promises exchanged by both sides. The legal classification depends on the actual words and law.
Can a unilateral offer be withdrawn?
Rules differ by jurisdiction and by whether someone has begun the requested act. Review the offer and get local advice before withdrawing a material live campaign.
Are sales bonuses unilateral contracts?
Some incentives may be structured that way, but employment terms and local law matter. Do not classify every bonus as a unilateral contract without reviewing its conditions.
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