The Swiss authorities online
A tax certificate showing the AHV pension income you have received is sent out automatically at the beginning of the year. Occupational pension funds will also provide you with a tax certificate every year. This will allow you plenty time to complete your tax return.
If you need a copy of your AHV tax certificate at any other time, you can order one from the compensation office that is currently paying your pension. You will find a list of compensation offices on the AHV/IV website.