I believe the chief question will be where exactly in the wording of the joining-document....did they give the EU authority over their state taxation rules.
I believe what will happen though....over and over...the EU or it’s EU-court device....will continue to say that they have some authority over taxes. At some point, a dozen countries out of the EU will stand up and just say ‘no’....there is no such authority and challenge legitimate nature of the EU on taxes.
It’s the same with the EU needing to establish toaster regulation in the past couple of months. You just start laughing at what the EU chooses to get involved in. They need to just bring their legislative members in for 90 days a year and force them to return home for the remainder of the year.
This is what happens when people in an inherently unproductive and wasteful career such as government service are “productive”: they find ways to be even more wasteful and fussy.
“did they give the EU authority over their state taxation rules”
I know the EU has Value Added Taxation rules with minimums.