I'm resident in Switzerland. Would I need to pay any tax in Switzerland on income earned from overseas assets (eg interest earned on overseas bank savings)

Thanks !

In short the answer is yes, but then if you don't declare it who will know anyway ?

Yes but if you bring it into the country, say to pay a deposit on a flat, are you then taxed on it?

Depends how much you are bringing in i guess. If it's a million then whichever bank you store it in will be more than happy to advise, if it's a few thousand francs, who cares ?

You would pay income tax on any interest and wealth tax on the amount itself. The flat, less mortgage, would be part of your taxable wealth.

Wealth tax is fairly low, but the authorities may be puzzled where it came from if not declared in previous years. You could say it was a gift/inheritance which is likely tax-free, but check you cantonal rules before declaring...

yes, AbFab is correct - hide it now and you will have a problem unhiding it in a reasonable manner in the future...

This is very true. It is best to find out what the tax free limit is where you are living and then to transfer or declare that amount, or better said slightly less. Once you purchase a house your debts will reduce your net worth substantially

More to the point, you then have to explain where this sudden influx of wealth came from.

As others have said, think carefully before hiding it if you might to have to use it, in Switzerland, in the future.

Taking it a little deeper - what about the country where you have the bank account. Will you be decalring the interest there? If it's somewhere like the UK then the tax authorities know about that interest and it may even be deducted at source.

If you pay tax on the interest in another country, and Switzerland has a double tax agreement with that country, then you would probably not be liable to tax here if the other country has higher tax rates (you would still declare it but the tax you paid in the other country is then offset against what you may pay here).

It is relatively easy to keep the Swiss tax authorities at bay but a sudden lump of income could lead to questions you might want to avoid - once questions are asked, they will be tenacious .