Federal taxes owed?

Ok, heres the situation, I will try to be brief. My girlfried has been divorced for three years, was married for 15 years. Her husband worked as a contractor, so his pay never had any federal taken out. He was responsible for paying his taxes quarterly. She paid the max amount to offset what hed owe. Today she found out that hes only filed for the years 1993 and 1995 and that $12,000 is owed for just those two years. The IRS is going to start garnishing her wages after April 15th. She honestly did NOT know he didnt file and shes at a loss. Is there ANY recourse she can do? Thank you....