A more thorough explanation:

An Adoption Taxpayer Identification Number (ATIN) is a temporary nine-digit number issued by the Internal Revenue Service (IRS) for a child in the process of adoption. The ATIN is used as a unique identifying number for the child in the adoptive parents' federal income tax returns.

For example, if a child is in the process of adoption and the adoptive parents cannot obtain the child's Social Security Number (SSN), they may apply for an ATIN. The ATIN can be used to identify the child in the adoptive parents' federal income tax returns until the adoption process is finalized and the child is issued an SSN.

Another example is if a child is adopted from a foreign country and does not have a permanent resident alien card or certificate of citizenship, the adoptive parents may apply for an ATIN to use as a temporary identifying number for the child in their federal income tax returns.

These examples illustrate how the ATIN is used as a temporary identifying number for a child in the process of adoption when an SSN is not available or cannot be obtained.

Adoptive parents may apply for an ATIN by filing a Form W-7A with the IRS. The form must include the child's name, birth information, and the placement agency's information. Additionally, the placement documentation must be attached to and submitted with the form.

Once the adoption process is finalized and the child is issued an SSN, the adoptive parents must notify the IRS of the new SSN. The IRS will then deactivate the ATIN. If the ATIN is not deactivated within two years of issuance, the IRS will automatically deactivate it.

For more information about the ATIN, please visit the IRS webpage.