No taxes are due on a payout from a 3b fund account. It is comparable to withdrawing cash from your bank account. However, you must declare the current value of your fund account at the end of the year as assets in your tax return.
You may deduct your annual investments in your 3a fund account from your taxes up to the applicable maximum for pillar 3a contributions. The payout of your fund balance is taxed once only – separately from your other income and at a reduced rate that differs from canton to canton. Please consult the tax office in the canton where you reside.