If the court order states that she is supposed to let the child visit your husband needs to take her back for contempt. If the court order states that the two parties are supposed to alternate the tax deduction each year, then he needs to take her back for contempt. If he sits back and does nothing, nothing will be done. It does sound like fraud is being committed by her. Your husband also needs to go to the IRS and report this problem. I would immediately start by writing her a letter and saying the tax deduction is mine this year and I'm taking it and also I'm coming this weekend at 6:00 p.m. or whatever the court order says. Then I would send a letter each time she doesn't let the child visit. Then if it continues take her back for contempt for both problems.
There are many factors that can affect how best to handle this matter and the best advise is usually to hire an attorney immediately. Unfortunately the advice above is a guess that is based on very scanty facts. Circumstances of all sorts can change the ultimate answer you need. If you want to know how best to handle the situation, make an appointment with an attorney and get good solid advise based on more exact facts. The money spent might give you the peace of mind you need. The information provided is not intended as legal advice that can be relied on in part because we do not have the entire the situation. No Attorney/Client relationship is intended, implied or created. We are a debt relief agency and we help people file for relief under the bankruptcy laws.
If true, what she is doing is considered fraud. You may report what you suspect to be tax fraud activity to the IRS. That should be an effective means in flagging the SSN for future claims.
Fill out Form 3949-A. See directions on the following link: http://www.irs.gov/Individuals/How-Do-You-Report-Suspected-Tax-Fraud-Activity%3F
The reason it has not been picked up yet is probably because it is low priority or no one has alerted the IRS. If the child had been claimed on more than one return in a year, the IRS cross-matching system would pick that up. Otherwise you would have to raise it to the IRS.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature. Visit Steve Zelinger's website: http://www.stevenzelinger.com/