Form 8615 must be filed for any child who meets all of the following conditions.
1. The child had more than $2,200 of unearned income (for tax year 2021).
2. The child is required to file a tax return.
3. The child either: a. Was under age 18 at the end of 2021, b. Was age 18 at the end of 2021 and didn’t have earned income that was more than half of the child's support, or c. Was a full-time student at least age 19 and under age 24 at the end of 2021 and didn’t have earned income that was more than half of the child's support.
4. At least one of the child's parents was alive at the end of 2021.
5. The child doesn’t file a joint return for 2021.
These rules apply if you’re legally adopted and 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.