# Unilateral Contract: Definition, Examples, and How It Differs From Bilateral Contracts Published: 2026-02-24 Author: Warren Team URL: https://www.heywarren.com/blog/unilateral-contract --- A unilateral contract is a legal agreement where one party makes a promise in exchange for the other party's performance of a specific act — not a promise to perform. The contract becomes binding only when the second party actually performs, not when they agree to do so. This seemingly technical distinction has significant practical implications for finance, insurance, and commercial agreements. ## What Is a Unilateral Contract? In a unilateral contract, one party (the offeror) makes an open offer to the world or to a specific party: "I will pay you X if you do Y." The second party (the offeree) is not obligated to do anything — but if they choose to perform the specified act, the offeror must pay. **Defining characteristics**: - Only **one party makes a binding promise** at the outset - The other party accepts by **performing the act** — not by promising to perform - The contract is not formed until performance begins or is complete - The offeror can typically revoke the offer at any time **before** the offeree begins performance **Classic example**: "I'll pay $500 to whoever finds and returns my lost dog." This is a unilateral contract: - Only one party (you) made a promise - Anyone who finds the dog can accept by performing (returning it) - No one is obligated to look for the dog - Once someone begins searching, most courts hold the offer cannot be revoked ## Unilateral vs. Bilateral Contracts The distinction matters legally and practically: | Feature | Unilateral Contract | Bilateral Contract | |---|---|---| | How formed | One party promises; other performs | Both parties exchange promises | | When binding | Upon performance (or start of performance) | Upon mutual agreement | | Obligations | Offeror pays when act is done; offeree has no obligation | Both parties have enforceable obligations from the start | | Can offeree be sued for not performing? | No — they never promised anything | Yes — both are bound | | Common examples | Reward offers, insurance policies, options | Employment contracts, sales agreements, mortgages | ## Financial Applications of Unilateral Contracts ### Insurance Policies ![Common financial instruments structured as unilateral contracts, where only one party bears an obligation.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20760%20211%22%20width%3D%22760%22%20height%3D%22211%22%20role%3D%22img%22%3E%3Ctitle%3EHierarchy%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Crect%20x%3D%22300%22%20y%3D%2220%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22%232563eb%22%2F%3E%3Ctext%20x%3D%22380%22%20y%3D%2254%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2214%22%20font-weight%3D%22700%22%20fill%3D%22white%22%3EUnilateral%20Contracts%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20110%20105.5%20L%20110%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%2230%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22110%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EInsurance%3C%2Ftext%3E%3Ctext%20x%3D%22110%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EInsurer%20obligated%3B%20policy%E2%80%A6%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20290%20105.5%20L%20290%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22210%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22290%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EOptions%3C%2Ftext%3E%3Ctext%20x%3D%22290%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ESeller%20obligated%3B%20buyer%20h%E2%80%A6%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20470%20105.5%20L%20470%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22390%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22470%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EPerf.%20Bonuses%3C%2Ftext%3E%3Ctext%20x%3D%22470%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EEmployer%20pays%20if%20target%20i%E2%80%A6%3C%2Ftext%3E%3Cpath%20d%3D%22M%20380%2078%20L%20380%20105.5%20L%20650%20105.5%20L%20650%20133%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%20fill%3D%22none%22%2F%3E%3Crect%20x%3D%22570%22%20y%3D%22133%22%20width%3D%22160%22%20height%3D%2258%22%20rx%3D%228%22%20fill%3D%22white%22%20stroke%3D%22%230891b2%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22650%22%20y%3D%22158%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2213%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EProperty%20Options%3C%2Ftext%3E%3Ctext%20x%3D%22650%22%20y%3D%22176%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ESeller%20obligated%3B%20buyer%20c%E2%80%A6%3C%2Ftext%3E%3C%2Fsvg%3E) *Common financial instruments structured as unilateral contracts, where only one party bears an obligation.* Most insurance policies are classic unilateral contracts: - The insurer promises to pay claims if specified events occur - The policyholder is not obligated to pay premiums — they can lapse the policy - Only the insurer has a binding obligation (to pay if a covered event happens) - The policyholder "performs" by paying premiums, which keeps the contract in force This is why insurance policies are sometimes called aleatory contracts — the actual exchange depends on uncertain future events. ### Options Contracts An options contract is a financial instrument with unilateral characteristics: - The option seller (writer) is **obligated** to perform if the buyer exercises - The option buyer has **the right but not the obligation** to exercise - The buyer "pays" upfront (the premium) for this asymmetric structure Until the option is exercised, only one party — the seller — has an obligation. Once exercised, the contract becomes bilateral. See our guide on [notional value](/blog/notional-value) for how options exposure is measured. ### Reward Programs and Bonuses Performance-based bonuses in employment often have unilateral characteristics: - Employer: "If you hit $5M in sales, you earn a 10% bonus" - Employee: Not obligated to hit the target - If they do, the employer is bound to pay Similarly, many incentive structures for executives (like RSUs with performance conditions) follow this logic — the company promises to issue shares if performance thresholds are met, but no promise is extracted from the employee in return. See our guide on [RSUs](/blog/stock-rsu) for how these work. ### Real Estate Option Agreements A property option is a classic unilateral contract in real estate: - The seller grants the buyer the **right** to purchase the property at a fixed price within a set period - The buyer pays a fee for this option - The seller is **obligated** to sell if the buyer exercises - The buyer has **no obligation** to buy ## Revocation of Unilateral Contract Offers One of the trickiest legal issues with unilateral contracts is when the offeror can revoke: ![When a unilateral contract offer can be revoked depends on how far along performance has progressed.](data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20800%20149%22%20width%3D%22800%22%20height%3D%22149%22%20role%3D%22img%22%3E%3Ctitle%3ETimeline%3C%2Ftitle%3E%3Crect%20width%3D%22100%25%22%20height%3D%22100%25%22%20fill%3D%22%23f8fafc%22%2F%3E%3Cline%20x1%3D%22166.66666666666669%22%20y1%3D%2255%22%20x2%3D%22633.3333333333334%22%20y2%3D%2255%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%223%22%2F%3E%3Ccircle%20cx%3D%22166.66666666666669%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22white%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22166.66666666666669%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22%230f172a%22%3E1%3C%2Ftext%3E%3Ctext%20x%3D%22166.66666666666669%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EOffer%20Made%3C%2Ftext%3E%3Ctext%20x%3D%22166.66666666666669%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3ERevocable%20anytime%3C%2Ftext%3E%3Ccircle%20cx%3D%22400.00000000000006%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22%232563eb%22%20stroke%3D%22%232563eb%22%20stroke-width%3D%223%22%2F%3E%3Ctext%20x%3D%22400.00000000000006%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22white%22%3E2%3C%2Ftext%3E%3Ctext%20x%3D%22400.00000000000006%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EPerformance%20Begins%3C%2Ftext%3E%3Ctext%20x%3D%22400.00000000000006%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EOffer%20becomes%20irrevocable%3C%2Ftext%3E%3Ccircle%20cx%3D%22633.3333333333334%22%20cy%3D%2255%22%20r%3D%2224%22%20fill%3D%22white%22%20stroke%3D%22%23cbd5e1%22%20stroke-width%3D%222%22%2F%3E%3Ctext%20x%3D%22633.3333333333334%22%20y%3D%2260%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2215%22%20font-weight%3D%22700%22%20fill%3D%22%230f172a%22%3E3%3C%2Ftext%3E%3Ctext%20x%3D%22633.3333333333334%22%20y%3D%22101%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2212%22%20font-weight%3D%22600%22%20fill%3D%22%230f172a%22%3EPerformance%20Complete%3C%2Ftext%3E%3Ctext%20x%3D%22633.3333333333334%22%20y%3D%22119%22%20text-anchor%3D%22middle%22%20font-family%3D%22system-ui%2C-apple-system%2Csans-serif%22%20font-size%3D%2210%22%20fill%3D%22%2364748b%22%3EContract%20fully%20formed%3B%20of%E2%80%A6%3C%2Ftext%3E%3C%2Fsvg%3E) *When a unilateral contract offer can be revoked depends on how far along performance has progressed.* **Before performance begins**: Generally, the offeror can revoke at any time — the offeree has made no commitment and can walk away too. **After performance has begun**: Courts in most jurisdictions hold that once an offeree has begun performance, the offer becomes irrevocable for a reasonable period to allow completion. This protects the offeree from having the "rug pulled out" mid-performance. **Completed performance**: The contract is fully formed and the offeror must pay — revocation is no longer possible. ## Unilateral Contracts in Practice: Key Considerations **Specificity of the act**: The required act must be clearly defined. Vague offers ("I'll pay you if you help me out") are difficult to enforce because the required performance is unclear. **Acceptance by performance only**: A unilateral contract offeree cannot "accept" by saying "I'll do it" — they must actually do it. Promising to perform does not create a bilateral contract unless the offeror explicitly seeks a promise rather than performance. **Consideration**: Even in unilateral contracts, consideration is required. The offeror's promise is the consideration for the offeree's performance; the performance is the consideration for the offeror's promise. For related contract concepts, see our guide on [mutual exclusivity in contracts and finance](/blog/mutual-exclusivity). ## Authoritative Sources For deeper background and primary-source data on this topic, the following authoritative sources are useful starting points: - [IRS](https://www.irs.gov/) - [SEC](https://www.sec.gov/) ## Conclusion Unilateral contracts are promises contingent on performance — they create one-sided obligations that only become binding when the other party acts. They underpin many of the financial instruments and incentive structures investors encounter: insurance policies, options, reward mechanisms, and performance bonuses. The key distinction from bilateral contracts is that the offeree makes no promise and has no obligation — their "acceptance" is the act of performing. Understanding this structure helps investors assess the obligations, risks, and contingencies embedded in financial agreements. Warren at [heywarren.com](https://heywarren.com) helps investors understand the contractual and legal structures that affect investment value — from options to insurance to executive compensation arrangements. --- ## Related Reading **More from Warren**: - [Mutual Exclusivity: What It Means in Finance and Contract Analysis](/blog/mutual-exclusivity) - [RSU (Restricted Stock Unit): How Equity Compensation Works and Its Tax Implications](/blog/stock-rsu) - [Notional Value: What It Means in Derivatives and Why It Matters](/blog/notional-value) **Authoritative sources**: - [Cornell Law School — Legal Information Institute: Unilateral Contract](https://www.law.cornell.edu/wex/unilateral_contract) - [Restatement (Second) of Contracts — American Law Institute](https://www.ali.org/) - [SEC — Investment Contracts](https://www.sec.gov/investor/pubs/howregistrationworks.htm)