John McManus, one of Ireland’s richest, has a $5.22 million problem.

The 64-year-old Irish businessman is going after the United States government that he claimed has “wrongfully withheld” $5.22 million to cover the taxes of his $17.4 million gambling winnings.

Website Law360 reported that McManus filed a complaint at the U.S. Court of Federal Claims last Monday. In the complaint, McManus alleged the person who owed him his winnings had “erroneously withheld the money and the Internal Revenue Service has agreed to refund it but has been dragging its feet.”

The story went like this: McManus won the money in 2012, but the payer mistakenly sent $5.22 million to the IRS as withholding. So the businessman filed a non-resident U.S. federal income tax return, in which he emphasized that he is entitled to a refund because of a tax treaty between the U.S. and Ireland.