I have a property in a foreign country. I used the price equivalent in CHF for my 2018 Swiss tax filing. As Swiss franc has gone up against the foreign currency over 2019, I used an adjusted (lower) price in CHF on my 2019 fillings. In the tax documents that I got from Swiss authorities, they have used the same property value I filled in 2018 for my 2019 calculations and did not take into account the adjusted lower value that used on my 2019 filings.

I am new to Swiss taxes and I would appreciate if anyone in the forum could share their experience/expertise on this topic.

Thank you in advance,
John

What kind of value for the property did you use first? For this, I'd recommend speaking with a professional accountant. You would typically use some kind of "book value" with a little discount, close to the purchase price, not a market value (which includes, in all likelihood, some gains you've made in the past if your house's value increased). The administration expects the value of the house that you use for taxation purposes to remain the same year by year...

Appeal the decision if it will make any difference to the taxation. I fill in the values in the software in GBP and let it do the conversion. My valuation in CHF is different every year and it's never been questioned.
Any savings accounts in the UK will also obviously change in CHF worth from year to year.

So what to do if you bought a house 20 years ago and it was worth say 60,000 CHF then and now its worth 1,000,000?

If the property is in a place where the local tax authorities will give you an assessed value for tax purposes it is easy. For my US property, I just include a copy of the yearly property tax bill. This includes an assessed value which is approximately 20% of Market Value in my case. Swiss tax authorities have never questioned it.

In Australia they have a tax on the land. Not whats on the land. So they assess the value of the land for tax purposes.( the tax ends up astronomical for non residents ! )

Very sensibly they don't want non residents hoarding land.

one gets a provisory tax bill based on 2018 and pays that. Then one puts in the tax return for 2019 and they refund any money based on that return. ( if the calculated tax is lower than 2018.) And of course you might just have to pay extra