An Adoption Taxpayer Identification Number (ATIN) is A short lived nine-digit number issued through the IRS to people who are in the process of legally adopting a U.S. citizen or resident little one but who cannot get an SSN for that little one in time to file their tax return. https://cristian0h4i5.wikififfi.com/1312548/tax_lien_things_to_know_before_you_buy