Selling property in Bonstetten: houses counted, flats no longer

It is based on 16 open-market sales, just above the threshold of 15.² At the median a detached house cost CHF 1,250,000, about 21 per cent less than the cantonal median of CHF 1,590,000. In 2015 and 2007, with 12 and 9 sales, there was no house median.

Per square metre of plot, the median of the houses sold was CHF 3,835.⁷ The canton's model for undeveloped residential land gives CHF 2,335 for Bonstetten. These are two different measures. One is a median of prices paid for houses including the building, the other a model value for land without a house. They can neither be added nor offset against each other.

With so few cases, a few large or new houses can shift the median. What this means for you: the median is a reference point for Bonstetten, not a price for your house. Whether your house lies above or below it depends on plot, location, condition and fittings.

Because only 11 flats were sold on the open market, four below the threshold of 15.² In 2015 there were 17, with a median of CHF 430,000. In 2007, 83 flats changed hands, more than in either of the two later reference years.

What lies behind the 83 sales of 2007 the statistics do not say. One possibility is that many new flats were sold at the same time. Only the three reference years are evaluated here, not the years in between. Whether 2025 was an unusual year cannot be read from them.

The district of Affoltern remains as the surroundings. Its flat median is built from sales across the whole district. It rose from CHF 847,500 in 2015 to CHF 1,150,000 in 2025, by 36 per cent.² What this means for you: the district figure shows the surroundings, not the price of your flat. That comes from location, size, condition and comparable properties.

The canton sets the tariff; Bonstetten levies the tax.¹ 10 per cent applies to the first CHF 4,000 of gain, 40 per cent to every franc above CHF 100,000. In the example, 10 full years of ownership cut the tax by 20 per cent, to CHF 88,320.

After 20 full years the reduction would be 50 per cent, the maximum, and the tax CHF 55,200.¹ Anyone who bought more than 20 years ago may use the market value of 20 years ago as the purchase price. Only documented value-enhancing investments reduce the gain; plain maintenance does not.

Suppose you sell your house and buy a flat in Switzerland that you live in yourself. The tax can then be deferred, provided you also lived in the house yourself.¹⁰ If the flat costs less than the proceeds, the difference is taxed at once. If it costs no more than the house plus investments once did, there is no deferral. Deferred is not waived.