An Adoption Taxpayer Identification Number (ATIN) is A brief 9-digit number issued via the IRS to individuals who are in the process of legally adopting a U.S. citizen or resident little one but who can't get an SSN for that little one in time to file their tax return. A https://pmaccounting16047.wikifrontier.com/7979227/tax_id_number_no_further_a_mystery