Ok for the second year in a row someone claimed my children on there tax's and I am sitting here without my return. I have no idea were to start or even how to resolve this problem. When I spoke to the IRS last year I was told it would be investigated and my kids information would be red flagged in the system and that no one would be able to claim them without some type of pass word protecting my return. I am a single mother who has worked and supported my children on my own. I am positive it is not my x-husband as he is homeless on the streets but I do believe it is someone is his family and I want to stop this and see if I can press criminal charges on these thieves! Any information or answers are greatly appreciated.

Submit your tax return and hope that you get your refund in a reasonable amount of time. Other than that, it is out of your hands.

The IRS will investigate the problem and assess the appropriate penalties (probably fines).

You can not stop someone to claim your kids.
If you think that you are the one who can claim the dependent, then file your tax return and claim the dependent. It you are unable to efile, then send paper return. IRS with then contact both of your and figure out who must amend the tax return and pay the tax due with interest and penalty.

Only the custodial parent can claim the child. It does not count who is paying child support. The custodial parent is the parent with whom the child lived for the longer period based on the nights spent. The other parent is the non-custodial parent. Non-custodial parent can claim the child only if the custodial parent signs a release Form 8332 or there is a court order meeting the IRS requirement. Your U.S. Tax Return: Child of separated or divorced parents (http://taxipay.blogspot.com/2008/03/child-of-separated-or-divorced-parents.html)