What are the facts?
Cook was a real estate salesperson affiliated with Coldwell Banker/Frank Laiben Realty Co. At the outset of the sales year, Coldwell Banker publicly announced a year-long incentive program that promised additional compensation (a bonus/extra commission) to agents who met specified production thresholds by year's end. The announcement was made to induce increased sales effort and was framed as a reward for hitting enumerated levels of sales or commissions during the calendar year. As the year progressed and agents were working toward those goals, management later announced—around September—that payment would be made at the company's awards banquet the following spring and that only agents still affiliated with the firm at the time of payout would receive the bonus. Cook continued to perform, met the specified production requirements by the end of the year, and thereby qualified for the promised bonus under the original program terms. Before the awards banquet and the deferred payout date, however, Cook left the firm to join another brokerage. Coldwell Banker refused to pay the bonus on the ground that Cook was no longer affiliated with the company at the time of the banquet. Cook sued for breach of contract (and in the alternative, relied on promissory estoppel), contending she had accepted the offer by performance and that the late-added continued-employment condition was ineffective. The trial court entered judgment for Cook, and Coldwell Banker appealed.
What is the legal issue?
Whether an employer that offers a year-end bonus as an inducement for sales performance may later impose a continued-employment-at-payout condition and deny payment to a salesperson who met the performance criteria but left the company before the scheduled payout date.
What rule applies?
A promise of a bonus in exchange for specified performance creates an offer for a unilateral contract that is accepted by performance. Under Restatement (Second) of Contracts § 45, once the offeree begins the invited performance, an option contract is created that makes the offer irrevocable for a reasonable time to complete performance; upon completion of the required performance, the offeror is bound. The offeror cannot unilaterally add material conditions after the offeree has begun (or completed) performance absent the offeree's assent and separate consideration. An employer may not withhold earned compensation by retroactively imposing a continued-employment condition that was not part of the original offer.
What did the court hold?
The bonus program formed a unilateral contract that Cook accepted by performance. The later attempt to condition payment on Cook's continued affiliation with Coldwell Banker at the time of the awards banquet was ineffective. Cook earned the bonus by satisfying the program's stated performance requirements, and Coldwell Banker was obligated to pay.
What is the reasoning?
The court characterized the bonus plan as a unilateral offer: Coldwell Banker sought to induce heightened sales by promising a defined bonus upon attainment of objective production thresholds. Acceptance was to be manifested not by a return promise but by doing the specified acts—hitting those thresholds by year's end. Cook began performing under the program when she pursued and closed sales in reliance on the announced incentive. Under Restatement § 45 and Missouri law, once the offeree begins performance in response to an offer inviting performance, the offer becomes temporarily irrevocable; the offeror cannot revoke or materially modify the terms to the detriment of the offeree who is already performing. Moreover, once Cook completed performance by meeting the year-end benchmarks, the unilateral contract was fully formed and Coldwell Banker's duty to pay matured. Coldwell Banker's later pronouncement that agents had to be "actively affiliated" at the spring awards banquet to receive the bonus was a material modification that lacked consideration and Cook's assent. The purported condition did not relate to the performance the offer originally demanded (i.e., making sales/achieving thresholds) but instead sought to add a new prerequisite to payment after Cook had already been induced to perform. The timing of the award banquet and the deferred payout were administrative details; they did not transform continued employment into a condition of earning the bonus when the core performance—achieving the stated production goals—was complete. At-will status did not authorize the employer to forfeit already-earned compensation. Because Cook qualified under the original program and the modification was ineffective, the refusal to pay constituted a breach. The judgment for Cook was therefore affirmed.
Why is this case significant?
Cook solidifies the modern approach to unilateral contracts in the employment/independent-contractor context: bonus and commission plans are enforceable when they contain definite terms and invite performance, and employers cannot retroactively add forfeiture conditions after performance has begun or been completed. The case also underscores that at-will employment does not permit employers to withhold compensation that has already been earned under an existing offer. For students, Cook is a blueprint for analyzing incentive-plan disputes—identify the offer, the invited mode of acceptance, the point at which performance began, and whether any alleged modification is supported by consideration and assent.
Why is Cook v. Coldwell Banker taught as a unilateral contract case rather than a bilateral contract case?
Because the employer's promise sought acceptance through performance (hitting defined sales thresholds), not by a return promise to remain employed or to undertake specific actions. The structure was: if you perform (achieve X by year's end), we will pay a bonus—classic unilateral contract formation and acceptance by performance.
Could Coldwell Banker have lawfully required continued employment as a condition to the bonus?
Yes—if that condition had been part of the original offer's terms communicated before agents began performing, and if the condition was clear and not contrary to public policy. Alternatively, after performance began, the employer could have added the condition only with agents' assent and new consideration. Adding it midstream without consideration was ineffective.
What role does Restatement (Second) of Contracts § 45 play in the decision?
Section 45 provides that beginning the invited performance in a unilateral contract creates an option contract, rendering the offer temporarily irrevocable and preventing the offeror from revoking or materially altering the offer while performance continues. The court relied on this principle to reject Coldwell Banker's attempt to add a new condition after Cook had started performing.
Would the outcome change if Cook had left before meeting the performance thresholds?
Likely yes. If she had not completed the performance required under the original offer, the duty to pay would not have matured. While § 45 may prevent revocation once performance begins, the offeree must still complete performance to accept and claim the bonus unless the offer's terms or other doctrines (e.g., substantial performance or waiver) apply.
Does Cook's at-will status defeat her claim to the bonus?
No. At-will status allows either party to end the relationship prospectively, but it does not allow the employer to retroactively deny compensation that has already been earned under an enforceable offer. Once Cook satisfied the bonus criteria, the company's obligation to pay became fixed.
Could promissory estoppel have supported recovery if the court had rejected the contract theory?
Yes, in principle. Cook undertook and continued substantial sales efforts in reliance on the bonus promise. If the promise was deemed insufficiently definite to form a contract, a court could still enforce it to avoid injustice, provided reliance was reasonable and foreseeable. In Cook, however, the court found a binding unilateral contract and did not need to rely on estoppel to affirm recovery.