I adopted three children in 2018. Their birth certificates where changed in 2018, but SSNs where not changed until 2019. Which name/SSN should I use on my 2018 taxes?

[jamesonk]

The changes with Social Security where started in 2018, but not finished until 2019.  Both the names and social security numbers have been changed.

[DDollar]

You should use whatever is correct now with the Social Security Administration.