Everyone who lives in CH has to pay for AHV/IV no mather if you work or not also you have to pay if you are disabled (depends on your income and financial funds). Minimum is around 900.- and if your Taxed Income is 38`300.- ,minus deductable disability costs it will be something around the minimum. p.a. There are some exeptions like diplomats or asylum seeker.

But i do think in this situation it should be different, because you are insured and you are reciving a pension already and all costs are covered.