Minors have to file taxes if their earned income is greater than $12,550 (increasing to $12,950 in 2022). If your child only has unearned income, the threshold is $1,100 (increasing to $1,150 in 2022). If they have both earned and unearned income, it is the greater of $1,100 or their earned income plus $350. If the minor is self-employed, they will owe self-employment tax at $400 and above.