How will I be penalized in court over €25000 tax arrears?

My mate lived in Munich for 20 years and run up a debt of £40,000, he went to court and said he was prepared to go to jail because he did not have the money to pay his tax bill, in court thay said we want the money so he left Germany came back to uk and has not heard anything since that was about 12 years ago, good luck...