IMO this 3a thing must be split into 2 separate (orthogonal) concerns:
- tax savings when paying into 3a
- how/whether to invest once the money is in 3a or if it’s better to invest outside 3a
So regarding 1.: I think that’s dependent on each person’s tax situation but obviously in many cases there are huge gains to be achieved - as you pointed out in your 2350.- example. So if you’re fine with this money being locked until you retire, build a house or leave Switzerland then that’s a great idea.
Regarding 2.: I just did a calculation yesterday here for a sample situation and the result for those numbers where: investing in 3a mutual funds/etfs has a tax advantage of 0.2% vs investing outside 3a in etfs. So, based on the chosen example numbers at least, dividend gain does not offset 0.5%, only 0.2%.
With that in mind (and yes, everybody’s numbers are slightly different, so everybody must calculate this themselves) I conclude: it is better to (a) pay into 3a to get the tax benefit but (b) keep just cash there and instead invest with what’s still outside of 3a. That is, for the amount of cash I want to keep as cash based on an overall (3a + outside-3a) portfolio view. So really, look at how much you want to invest in total, how much have emergency cash. Then keep a very minimalistic amount of cash outside of 3a (eg 5000) but invest everything else outside of 3a. If you want more emergency cash, keep that non-invested in 3a. And in case of an emergency do the investment-jugggle-trick I mentioned in the other thread