@mcruser got it.... are you aware of the PINs?
if you sign up for the PIN, only the person who submits the PIN with the efiled tax return can file electronically. (and presumably you are the only person that knows the PIN). The other person can't efile and is forced to paper file; might cause them to NOT add a dependent that they are not supposed to as the return will be closely scrutinized (because the IRS knows there is a PIN associated with your child's tax return and it wasn't on the paper filed copy by the perpetrator)..
it could really protect you going forward
https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin
