Questione giuridica chiave
Whether the 12 December 2002 tax assessment decision setting the VST refund claim to zero was void.
Decisione estratta
The decision was not void. At most it may have been incorrect, but it was appealable and became final unchallenged; no ground for revision or restoration of the appeal period was shown.
Motivazione estratta
Nullity is exceptional and requires a grave, obvious defect without endangering legal certainty. The alleged defect concerned only the merits and did not amount to a particularly serious or obvious defect. The taxpayers also failed to invoke any valid revision or reinstatement ground.