Why do I have to enter my parents social security number onto form 8615 if they are not claiming me as a dependent on their taxes?

[KathrynG3]

It depends. You may be subject to Kiddie Tax rules if your unearned income is more than $2,200. That means you will be taxed at a higher rate.

Click the link for more details: What is the 2019 Kiddie Tax? The rules were changed in December of 2019 with the passage of the SECURE Act. The change is retroactive for 2018, too.