In 1988 my father sold a home in California and moved to Alabama. He paid the property taxes, but he didn't pay the taxes on the profit he made off the house. Which was $2,000 then. Now it has ballooned to $37,000. There is a tax lien on all my father's property. My parents have know tax records from then. My mother recently retired. What can they do so the IRS doesn't take her retirement money and how can he clean this off his record?