What this notice is about We have important information about your child’s Adoption Taxpayer Identification Number (ATIN). We need more information to process your 1- year extension request of your child’s ATIN. What you need to do Complete Form 15100, Adoption Taxpayer Identification Number (ATIN) Extension Request PDF, included with your notice within 60 days, and provide: The reason you need an extension. The reason you can’t get a Social Security number (SSN). The status of your adoption. Original signatures of adoptive parents, or; The SSN for your child if you received it. Detach notice stub, mail it with Form 15100 in the envelope provided. If you prefer, you can fax it to the fax number in the notice using a fax machine or an online fax service. Several online fax services use the internet to send files form your computer or smart device to a fax number. You may want to Call us at the number listed in your notice. See additional information on Adoption Taxpayer Identification Number. Frequently asked questions What do I need to do? Send us the missing information so we can process your 1-year extension. How long is an ATIN valid? An ATIN is valid for 2 years. If you don’t have an SSN for your child, you can request a 1-year extension. For more information, see instructions for completing a Form W-7 A, Application for IRS Adoptions for IRS Individual Taxpayer Identification Number. Reference Tools Publication 1, Your Rights as a Taxpayer Full list of tax forms and instructions Need Help? You can authorize someone to contact the IRS on your behalf. See if you qualify for help from a Low Income Taxpayer Clinic. If you can’t find what you need online, call the IRS number at the top of your notice or letter.