The State can place a lien on an IRA to collect child support arrearages, yes.
yes
yes
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yup
Yep
For arrears, yes. see links below
A Springfield, MO Court placed a lien on the estate that a deceased father would have inherited from his parents, cutting any possibility of his older children, from his deceased first wife, from receiving anything. Answer Yes. Child Support Liens are an important tool in collecting arrearages. Although practices and resources for collecting child support arrearages may vary from state to state, the Uniform Interstate Family Support Act has been adopted by every state in the U.S. The Act establishes rules that require every state to defer to child support orders entered by courts in the child's home state. Every state has a means by which a lien can be attached to any property owned by an obligor. On a basic level, those liens capture wages, tax refunds, real property and motor vehicles. The property cannot be sold or refinanced unless the lien is paid off. However, many states have become quite persistent and creative in finding other assets that should be used to support children of delinquent parents. Following are some examples. Some states compare a list of obligors to lottery winners and hold back funds to pay arrearages. Some states restrict any type of license renewal until arrearages are paid. Some states search 1099s for IRA accounts. NJ has attached the award in a pending class action suit against US Steel. A Kentucky court ruled that a father's obligation was not terminated by his death. Maryland has a standard procedure for attaching an obligor's inheritance. The state of Florida discovered an obligor was the beneficiary of a NY trust and was able to enforce a judgment against the trust for arrearages and garnishment for future monthly payments.
In Illinois, yes, even if the child support obligor transfers his IRA into a new spouse's name. See Takata v Hafley at http://www.state.il.us/court/Opinions/AppellateCourt/2008/3rdDistrict/June/3070175.pdf
yup
No, the IRS does not have the legal power to take such action.
IRAs can be seized for child support. I suggest that you contact your State's child support agency. When you get an interview with them, bring all the papers relating to your child support: birth certificates, acknowledgments of paternity, court orders, payment records, etc. Be polite but persistent. Good luck!
An IRA is a retirement account for which there are heavy tax penalties for early withdrawal--and that is if you are willing. Most likely tax qualified retirement assets are protected from judgments and garnishments.