The child has to have either an ITIN or a Social Security number to be claimed as a dependent on a tax return. And the ITIN must be issued before the due date of the tax return For tax year 2024 the due date is April 15, 2025.
Go to this IRS website for a Form W-7, Application for IRS Individual Taxpayer Identification Number - https://www.irs.gov/forms-pubs/about-form-w-7
