Few recent U.S. Supreme Court rulings have hit American expat taxpayers, and the experts who advise them on tax matters, as powerfully as last Tuesday's decision in a long-running FBAR case involving a "non-willful" dual citizen named Alexandru Bittner.

In what many tax lawyers and others have long hoped it would do, the U.S. Supreme Court has at last agreed to consider a so-called "non-willful FBAR penalty" case, which is expected to result in clarification as to how the penalties in such non-willful FBAR matters should be determined.

A U.S. taxpayer has been hit with almost US$13m in FBAR penalties, following a U.S. District Court ruling in Florida earlier this month, in what experts say is one of the largest individual FBAR assessments ever.