It is legal and I'm doing it all the week. I invoice my onshore corps on a regular basis and have done that for years. No one has asked questions as per today's date!
I would go with a Cyprus company if you operate in Europe, it's even more trustworthy and there are huge differences and + benefits compared to Bulgaria and Malta and even the Baltic countries.
I have used offshorecorpgroup.com for all my setups. In your case you need to setup a non resident Cyprus company with foreign nominees, that's what you want.
I'm setting up a Belize company while we speak, it seems to offer the best privacy for "non dark" use! I have setup 2 Seychelles corps with darks which was easy, they are some great tools to work with in a bigger setup.
So you think it would be better to get out of the crypto market before Q4 2018 ? I agree with what you wrote, but it's a shame if this already stops while it just got started.
What ICO will be the next great investment to cash in?
Do you have any idea or read about one, then please post information and link here, I'm interested to make some large investments in new ICO's
you have a great point here. What would you say is the best way to transfer large sums if you want to keep the money offshore and out of the view of your tax office?