I know at least a couple of people this started happened to suddenly in 2012. I don't think it is a coincidence. You should spread the word warning people. I am going to write letters to my congressperson and senators, complaining about this law. It is a violation of due process and is ex post facto.
In 2008, a new federal law was passed to allow the Department of the Treasury to collect from debts older that 10 years.
This law was passed as part of "The Food, Conservation and Energy Act of 2008".
This probably effects the disability and low-income communities disproportionately.
https://www.federalregister.gov/articles/2009/12/28/E9-30550/offset-of-tax-refund-payments-to-collect-past-due-legally-enforceable-nontax-debt
Here are some news reports that lead me to finding the law.
http://www.nbcchicago.com/investigations/us-treasury-irs-statute-limitations-tax-grab-208436421.html
http://www.usatoday.com/story/news/nation/2013/05/06/mother-social-security-debt/2138219/