How do I report my dependent 22 year old college student's earnings on Turbo Tax?

A child income is reported in the same way anyone else's is. You would follow the same procedure of filing her return as you do your own. You would indicate that she is being claimed as a dependent in the Personal Info section at the beginning.

 

Tax filing requirement (for dependents)

The minimum income requiring a dependent to file a federal tax return. 2020 filing requirements for dependents under 65: Earned income of at least $12,400, unearned income (like from investments or trusts) of at least $1,100, or self-employment income over $400.

You do NOT report his/her income on your return. If it has to be reported, at all, it goes on his own return. If your dependent child is under age 19 (or under 24 if a full time student), he or she must file a tax return for 2020 if he had any of the following:

1.          Total income (wages, salaries, taxable scholarship etc.) of more than $12,400 (2020).
2.          Unearned income (interest, dividends, capital gains, unemployment) of more than $1100.
3.          Unearned income over $350 and gross income of more than $1100
4.          Household employee income (e.g. baby sitting, lawn mowing) over $2100 ($12,400 if under age 18)
5.          Other self employment income over $432, including money on a form 1099-NEC

 

Even if he had less, he is allowed to file if he needs to get back income tax withholding. He cannot get back social security or Medicare tax withholding.

In TurboTax, he indicates that somebody else can claim him as a dependent, at the personal information section.

 

What you may have heard of is this: If his only income is from interest and dividends, Alaska PFD or capital gains distributions shown on a 1099-DIV, there is a provision for entering it on your return, using form 8814. Enter at Less common income / Child's income.