if the child was on your 2020 TurboTax return the SSN should transfer when doing 2021. I believe that an IRS transcript of your 2020 return will only show the last 4 digits. if you call them and get through they will not release the child's SSN. if you didn't use TurboTax but filed a return, it may be on it but in some cases, only the last 4 digits show. if the child was born in 2021 only the Social Security Adm will be able to supply you with the number and that will require contacting a local office for an in-person visit. they will require documentation such as a birth certificate
