Making an offer on a house: what belongs in it and when it binds

A written offer names the property, the price and the handover date you want. It also covers how the land registry costs are split and the amount of any deposit. What applies if one side withdraws belongs in it too. This is how UBS describes it in its guide (retrieved September 2026).

Proof that you can finance the price is important. UBS gives an irrevocable payment promise from your bank as an example. Conditions are also common, such as the final mortgage or the sale of your current property. A condition means the offer only stands if that point is met.

An offer needs no particular form. Even so, put it in writing, so it is clear what you offered.

What this means for you: the more complete your offer, the easier it is for the owners to compare it. A deadline for how long it stands adds clarity.

An offer on a property does not oblige you to buy. Contracts for the purchase of land are only valid if they are publicly notarised (Art. 216 para. 1 Code of Obligations, Obligationenrecht). Notarisation (Beurkundung) means signing before a notary.

A preliminary contract that promises a later purchase also needs this form (Art. 22 para. 2 and Art. 216 para. 2 Code of Obligations). So an offer, a letter of intent or a reservation does not bind you to buy. A penalty payment if you do not buy is invalid without notarisation. In judgment 4A_281/2014 of December 2014, the Federal Supreme Court (Bundesgericht) struck down such a claim for CHF 192,000.

Not binding does not mean without consequences. The owners plan around your offer. And other bidders are waiting for a decision.

What this means for you: bid in a way you can stand by. That is why, with us, a bid only counts as an offer with your bank’s confirmation.

A bidding round at Immosmile follows written rules that are the same for all. We call this the “Same round for all bidders”. All bidders receive the same documents at the same time. Every offer reaches the owners on the same day.

After each offer, the owners decide in writing: accept, hold a bidding round or keep marketing the property publicly. A bidding round requires at least two serious offers with checked financing. Everyone receives the deadline and the rules in writing beforehand. Details of your offer are not passed to other bidders. There are no fictitious bids to drive up the price. In the end, the owners decide freely, not automatically for the highest bid. The security of the financing counts too.

Immosmile acts solely for the owners; these rules do not create any advice or representation of your interests.

What this means for you: you know the rules before you bid. And no one receives more information than you.

No freely available, reliable statistic shows how far asking and selling prices differ in Switzerland. The asking price is the price in the listing. The selling price is what ends up in the purchase contract.

There are separate indices for both prices. But they do not measure the same properties. Wüest Partner records asking prices from around 600,000 listings a year, for rent and for sale. The prices paid come from other, real sales, over 20,000 a year for single-family houses (theonliner.ch, December 2022). A discount that applies to a particular house cannot be read from this.

Percentages circulating online mostly come from German advice sites or have no verifiable source. They say little about a house in the Canton of Zurich. Every property, location and level of demand is different.

What this means for you: do not rely on rules of thumb. This is not a recommendation on how much to bid. We do not give one.