From the IRS Instructions for Form 8615 - https://www.irs.gov/pub/irs-pdf/i8615.pdf
Who Must File
Form 8615 must be filed for anyone who meets all of the following conditions.
1. You had more than $2,100 of unearned income.
2. You are required to file a tax return.
3. You were either:
- a. Under age 18 at the end of 2018,
- b. Age 18 at the end of 2018 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 2018 and didn’t have earned income that was more than half of your support.
4. At least one of your parents was alive at the end of 2018.
5. You don’t file a joint return for 2018.
