A dependent child's income amount does not matter. She would still qualify as your dependent regardless of how much she made. The $4,050 is for people who are not a qualifying child.
Since she made more
than $6,300 income she must file a return. Anything less than $6,300 is not required to file but it is a good
idea to file a return to get back withholding. Be
sure she selects someone else can claim her as a dependent on her return.
https://ttlc.intuit.com/replies/3302077
