As large as it is, the building would be easy to miss. Plain, gray and near a McDonald's, it's part of a generic office complex surrounded by a vast parking lot in a suburb of Copenhagen. "Danish Tax Agency" is stenciled in both English and Danish on a glass front door.
This outpost of SKAT, as the I.R.S. in Denmark is known, seems an improbable setting for what the authorities call one of the great financial crimes in the country's history. For three years, starting in 2012, so much money gushed from an office here that it was as though the state had sprung a gigantic leak.
Prosecutors in Copenhagen say it was an elaborate ruse, one that ultimately cost taxpayers more than $2 billion — a spectacular sum for Denmark, the equivalent of a $110 billion loss in the far larger American economy.