As the person is a U.S. citizen they are required to report worldwide income, which means that they are required to report the sale of the property, even if it is in a foreign country. I asked about the other country because...IF the U.S. has tax treaty with that country, there usually are articles in the treaty that addresses the elimination of double taxation and capital gains. Without knowing what the other country is, I cannot tell if there will be double taxation. Since you do not wish to divulge the country, you can google U.S. Tax treaties
and see if the U.S. has a tax treaty with that country. If they do not, if you incurred a gain from the sale of the property, you will likely be taxed on that gain amount in the U.S.
As for the amount in the foreign account being over $10,000, this person is required to complete a Form TD F 90-22.1, Report of Foreign Bank and Financial Accounts (FBAR).
Actually this form should have been filed by June 30, 2013. You can refer to the following IRS webpage fore more information relating to the FBAR;
Please let me know if I can be of further assistance to you regarding this matter.
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