Hi alanmack,
The term pillar 3b is used by insurance companies to denote insurances which fall under the tax deduction for health, life, and disability insurance.
The problem is: This tax deduction is already nearly or fully taken up by your premiums for mandatory health insurance. So unless you have very low health insurance premiums (lower than is possible in Geneva, except possibly with premium reductions), pillar 3b insurance has zero tax benefit.
There is talk of raising the tax deduction to 3000 francs (6000 for couples), so if that happens, there will be a little more room to benefit.
My personal recommendation is that you stay away from permanent life insurance (the kind with cash value, which insurance companies market as a retirement saving and investment solution). It is inflexible and there are much cheaper ways to invest. Instead, use a cheap stock broker to invest in ETFs (or a cheap robo-advisor if you don’t like investing on your own). If you don’t want the risks of investing, then savings accounts and/or medium-term notes are good fixed-income options.
There are useful insurances - namely supplemental health insurance, term life insurance, disability insurance - which can make sense in some cases. If you have any of these and your mandatory health insurance premiums do not use up the full tax deduction, you can include their premiums to use up the full deduction. In the case of term life and disability insurances, you will have to get the pillar 3b versions (not the pillar 3a) to include them in the deduction for health, life, and disability insurance.
For retirement saving, the pillar 3a is a much more sensible vehicle, as both your income and wealth taxes benefit.
If you have extra money which you want to save for retirement on a tax-privileged basis in order to lower your taxes, then making voluntary contributions to your occupational pension fund (pillar 2) is an option.