Dex writes:
You must declare on your USA tax form if you have a overseas account and declare any income from it. It is taxable income.
Yes, you will need to file Form TD F 90-22.1 on any foreign accounts if the total is over $10,000. Note that you file the form directly with the Treasury, not with the IRS, though you can download the form from the IRS website.
The basis for the gain or loss on the sale of the asset (you could gain or lose money on the sale of the euros) is the date of death of her farther.
If she inherits cash, I don't think there is any need to worry about cost basis if she later converts that cash to dollars. That is a one-way exchange, so no gain/loss calculation applies as it would in a round-trip transaction. For example, when I earn yen, and later purchase dollars, this is not considered a taxable event, from what the IRS has told me. (To be precise, the earning yen part is of course taxable, but the later purchase of dollars at some different prevailing exchange rate is not a taxable event.) I think the inheritance discussed here would be treated similarly (though I could be wrong). If she inherits securities instead, then of course the cost basis at time of death applies.
By the way, Rich, if your wife decides to invest the money in Germany, she will probably want to avoid German mutual funds, for US tax reasons. Instead go for straight stocks, bonds, or other directly-held assets.
Bpp