Referring to WHT on 2nd pillar withdrawal when leaving CH. I understand you first pay the WHT in CH at a rate depending on the canton where your 2nd pillar fund is domiciled. If the DTA with the destination country says such withdrawal is taxable in the destination country you can claim back the WHT from CH. To do this I understand you need to demonstrate that you have declared the withdrawal in the destination country.
When I made the statement above but I was assuming the tax in the destination country is almost always going to be higher than the super low Swiss WHT. Perhaps I am over simplifying and there are some countries with lower rates? In addition I realised am not sure if it is a requirement to demonstrate that you declared the withdrawal in destination country or just to prove you are resident
There was some discussion in this thread