How can I let the IRS know that someone is filing my kid without permission

First off... depending on the situation... it might not be up to you to give permission or not..


Has there been a divorce... is there a custody order... what are the terms of the custody order and any support payments?

Those are important for any answer anyone can give you.

You file correctly with your child. If they have filed first, you do yours on paper and include documentation that you are the one suppose to file.

Just prove on your return that you are the correct person