If I was in a position to decide the appropriate penalty for significant tax evasion I would consider deportation- preferably to somewhere with very low rates of taxation.

Somalia, Haiti or the Central Republic of Congo may be suitable?

If you don't want to pay taxes you are free to go somewhere they don't have much government or taxation. None of you bleating Libertaian hypocrits ever do though.

Certainly tax evaders are bludgers and need some sanction on their sly freeloading robbery of all other citizens.