I don't know if I qualify for additional child tax credit?

[Bsch4477]

TurboTax will automatically calculate that if you are eligible. Look at line 28 of your 1040. 

[MinhT1]

The Child Tax Credit and the Additional Child Tax Credit are meant to help working parents with low to moderate incomes. For that reason, families must have a minimum of $2,500 of earned income to claim the ACTC. Earned income can come from salaries and wages, self-employment, and some disability payments. Parents whose income comes solely from "unearned" income — such as interest and dividends, pensions and annuities, social security, unemployment, alimony or child support — do not qualify.

Please read this TurboTax article for more information.