IRSN (Internal Revenue Service Number) – What It Is, Who Needs It and Who Should Avoid It.
Hundreds of thousands of American citizens by birth live abroad without a Social Security number. Many of them have recently discovered that they have U.S. tax compliance obligations. Most often this news is delivered by a foreign bank that has custody of their money, through ascary letter with the threat of freezing their funds unless they provide proof of U.S. tax compliance.
However – obtaining a Social Security number, even if you have all the required documents, may be a challenge for those living in remote parts of the world, far away from the nearest U.S. Embassy. But people need to catch up with their filing obligations ASAP and they search for a way to file without a Social Security number.
First they learn the acronym ITIN – Individual Tax Identification Number. The Application for an ITIN can be submitted by mail to the IRS along with the completed tax returns. This is the easy and speedy solution. Unfortunately, individuals eligible for a Social Security number are not eligible for ITIN – a tax ID for the foreigners. This option does not work for the US citizens by birth.
Whole story at TFE.