how much unearned income do you have and where did it come from ?

How old are you?

I'm 21, turning 22 in less than a month. My earned income for 2020 was about $8,000, but I live off of my VA education assistance (chapter 31) and disability (together roughly $1700/month), both of which are nontaxable and do not produce any sort of tax forms. I didn't have any issues with filing in 2019, in which I was in the same boat, and in 2018 I was on active duty in the military (only served 1 year due to injury), which I didn't have any issue filing for either.

It is unearned income that triggers Form 8615

"I have not been listed as a dependent on my parents' taxes since 2017."

are you sure you are not listed as a dependent on your own 2020 tax return ?

Where would I look to see if I made that mistake? On my personal info it shows my marital status as "single" which is correct. I know I didn't qualify for any education breaks since the VA covered my tuition, and I got an additional $7k in grants and scholarships, all of which I've documented in the deductions and credits section.

To check your dependency status, open TurboTax Online and: 

1. Click the Pick up where you left off button, if it’s present
2. Let the whole page load
3. Click the My info tab in the left pane
4. Click Edit to the right of your name
5. Midway down the page, you’ll see 3. A few other things we need to know -- Someone else can claim me as a dependent on their tax return.  Make sure you’d clicked the No bullet.

Here are the requirements for filing Form 8615, according to the IRS's Instructions for Form 8615.  Maybe this’ll help see what’s triggering the form.

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.

2. The child is required to file a tax return.

3. The child either:

a. Was under age 18 at the end of 2020,

b. Was age 18 at the end of 2020 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 2020 and didn’t have earned income that was more than half of the child's support. (Earned income is defined later. Support is defined below.)

4. At least one of the child's parents was alive at the end of 2020.

5. The child doesn’t file a joint return for 2020.

For these rules, the term “child” includes a legally adopted child and a stepchild. These rules apply whether or not the child is a dependent. These rules don’t apply if neither of the child’s parents were living at the end of the year.

I think I finally figured it out. When asked if I spent more than half of my earned income on living expenses, I guess I misunderstood and checked "no" since the majority of my income is from the VA and not "earned" income. I changed that to "yes" and Form 8516 finally vanished.