Thanks for tips Moorebonds!
We're living in Belgium though, so not all are applicable
In Belgium, once you pay yourself about 34K yearly, the fiscus will allow all the other fun things (such as renting your own home at market conditions). We do not have Roth IRA and such.
The greatest thing is that my brother is in software, and for intellectual property I found a nice getaway via an Hong Kong 'developing company' (Belgium and HK have a peculiar tax agreement here). Combine this with the fact that capital gains are untaxed in Belgium and it is not hard to imagine a way to get the company money in private hands without taxes! (However, we'll take fiscal advice on each step.)
So tax deductions are great, byt maybe he will hardly pay taxes to begin with
EDIT: You are speaking of advicing him on his best retirement options... well he knows about index> real estate in the past, but he is dreaming about living on landlord revenue while using 100% of his other income to increase the capital (/amount of rental units). Maybe not optimal, but if that's what he wants, I guess it will work out just fine.