The EU crypto transaction tax under review by the European Commission could put a 0.1% levy on crypto trades across the bloc, a small charge on paper that may have outsized consequences for traders, exchanges, and the European Union’s budget plans. The proposal, outlined in an internal document circulated on May 30, is projected to raise between €3 billion and €4 billion a year.

That makes this more than a niche tax story. Instead, it sits at the intersection of two major EU priorities: finding fresh revenue for the next long-term budget and tightening the framework around digital assets as crypto regulation in Europe has become more mature.

There is a catch, however, and it is a big one. The plan is not adopted, and getting it…