Unfortunately, the answer appears to be "yes." The fact that your father-in-law is a signatory is enough to give the IRS the ability to attach the account. If you can establish that the money does not belong to your father-in-law, however, it may be possible to get the money back from the IRS through an administrative claim or (if the claim is denied), through a civil lawsuit. I hope this helps.
Answered on Jul 16th, 2012 at 8:31 AM