Since you are NOT the custodial parent you can ONLY claim the kids if the custodial parent allows you to do so (even if they are not going to file a return) AND you only get the dependent exemption ( not allowed from 2018-2025) and the Child Tax Credit (& Additional CTC). You are NOT allowed HOH filing status, the day care credit or the EITC. To claim the kids the other parent must sign a form 8332 which must be attached to your return. These are the federal rules ... state rules may differ.
