International tax topics are littered with acronyms. In alphabetical order, and stopping at F, we have ATAD, ATAD II, BEPS, CBCR, CCCTB, CFC, DAC and FATCA.  A new one, not yet reduced to the sum of its initial letters in popular parlance, is the EU’s recent mention of “Fiscal Union”.  The EU Commission’s priorities for the next five years include Fiscal Union as a component part of its top-level priority “an economy that works for people”.  But what is it? Checks in the usual places (e.g. Ursula von der Leyen’s manifesto and her job description for the economics commissioner) give…