We had the VAT ID for businesses in place before that already and checked these against VIES, same for collecting two pieces of address, we have done that for a year already.

What are the exceptions for Azores etc? I didn't implement them, better check what the implications are.

I see the problem probably as an easier thing because I was able to roll it out bit by bit and only switch the tax codes over on Jan 1st. If one were to start from scratch now, that would be more annoying.