@Rachelcol If you cannot find your child's SSN on a past tax return, school document or record, etc., then you need to seek it from Social Security:
To Replace a Child’s Social Security card
https://faq.ssa.gov/en-US/Topic/article/KA-02723
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
