Why do I have to fill out form 8615 when I'm filing for myself?

Who Must File
Form 8615 must be filed for anyone who meets all of the
following conditions.

1. You had more than $2,200 of unearned income.
2. You are required to file a tax return.
3. You were either:
   a. Under age 18 at the end of 2019,
   b. Age 18 at the end of 2019 and didn’t have earned income
   that was more than half of your support, or
   c. A full-time student at least age 19 and under age 24 at the
   end of 2019 and didn’t have earned income that was more than
   half of your support.
   (Earned income is defined later. Support is defined below.)
4. At least one of your parents was alive at the end of 2019.
5. You don’t file a joint return for 2019.

These rules apply if you’re legally adopted or a stepchild.
These rules also apply whether or not you’re a dependent.
These rules don’t apply if neither of your parents were living at
the end of the year.