My bets are that this arrangement would almost certainly be considered tax dodging if the Dutch authorities ever find out (and he didn't pay taxes there). I'm n

My bets are that this arrangement would almost certainly be considered tax dodging if the Dutch authorities ever find out (and he didn't pay taxes there). I'm not a tax lawyer, much less a Dutch one, but I looked into similar things: the basic rule is that every country wants you to pay taxes there, and when in doubt you are usually taxable (which can easily mean that you're fully taxable on your global (!) income in more than one country - most developed countries have bilateral double taxation agreements to sort this out, but then you need to look into the specifics of said agreement - definitely something you should leave to a professional). If you spend more than half of the year in a country, you'll usually need a very good reason if you want to avoid being fully taxable there (in some countries it's a hard rule, some look at the circumstances). Just taking a two-day trip every month looks a lot like deliberately trying to dodge taxes - such things can easily lead to criminal charges.