At least in the EU, you pay the tax where the company is registered, or in case of individuals - where you declare your tax residency is. If you own a German construction company that occasionally drives across the border to France and builds houses there, you pay taxes on your earnings in Germany, of course. If you work for a Swedish company in Malmo, but actually commute every day from Copenhagen(I know a few people who do that) you pay taxes on your salary in Denmark, because that's where you live and where your tax residency is.