Is a verbal promise binding in business?

A promise is a contract, not a courtesy

Swiss law does not distinguish between a promise made across a desk and one made in a signed document. If the essential points are agreed and both sides intend to be bound, the contract exists — a salary increase promised in a year-end meeting, a discount assured on a call, a supplier's spoken commitment to hold capacity. The person who later says "but it was never put in writing" is usually making a proof argument, not a validity argument.

That has an uncomfortable flip side for whoever speaks loosely. Assurances given in meetings to keep a discussion moving — to an employee, a customer, a co-founder — can bind the company even though nobody intended to sign anything that day. In business, the safe assumption is that your words can contract.

Where writing is legally required

For a limited set of undertakings, the law makes written form a condition of validity, not merely of proof. Suretyship — promising to answer for someone else's debt — is the classic business example; certain other undertakings and clauses also require written or even notarised form, real-estate deals above all. In employment, specific arrangements such as a non-compete undertaking depend on written form, even though the employment contract itself does not. Where a form requirement applies, the oral promise is not a weaker contract — it is no contract.

The parties can also impose form on themselves: if a framework agreement says amendments must be in writing, an oral side-promise sits uneasily with the text, and disputes about which prevails are exactly the kind of fight you want to avoid.

Proof is the real battlefield

Most disputes over oral promises are not about the law but about the record. Months later, memories genuinely diverge: one side recalls a commitment, the other a possibility discussed. Without documents, the outcome turns on witnesses, plausibility and surrounding conduct — payroll entries, invoices, performance that only makes sense if the promise was made. That is an expensive way to establish something a two-line email would have settled.

The discipline that works is simple: confirm. A short message after the conversation — "as discussed, we agreed X from date Y" — creates a contemporaneous record, invites correction while memories are fresh, and costs a minute. If the other side confirms or stays silent and performs, the evidentiary picture changes entirely.

What to do

• Treat your own spoken assurances as binding, because they may well be — brief decision-makers before meetings on what may be promised.
• Confirm every material oral agreement in writing the same day, and ask for confirmation of promises made to you.
• Know the small list of undertakings that need written form — suretyship above all — and never accept those orally.

Whether a particular promise binds, and how to prove it, depends on the words used and what happened afterwards — if real money hangs on one, discuss the specifics with a lawyer before positions harden.