As I understand it is a withholding tax, rather than a savings tax. This means that when you do your tax return you inform them that you paid a certain amount of withholding tax and they will deduct it from the tax you have to pay (but they will of course count the interest you received as income).

Since the interest rate on CHF is almost nothing this won't be an issue for most people, unless we are talking about a very large quantity of CHF to start with, or you are holding a currency which earns more interest in a Swiss account.