Conversation so far:
what was the tax evasion with Ernie Kovacs about?
A frequent critic of the U.S. tax system, Ernie Kovacs owed the Internal Revenue Service several hundred thousand dollars in back taxes, due to his simple refusal to pay them.
how did the IRS find out about Ernie Kovacs's tax evasion?

Question: did he ever have to pay it back?
Self-contained rewrite: did Ernie Kovacs ever have to pay back the sveral hundred thousand dollars in back taxes, due to his simple refusal to pay them?