Is money earned from working in contracting companies that evade state taxes considered illicit gain?

If taxes are imposed unjustly and spent in ways not sanctioned by Islamic law, then there is no sin in evading them or reducing them. However, if they are legitimate and imposed by the state to meet the needs and interests of the nation, then it is not permissible to evade them or to resort to stratagems to reduce them. Accordingly, working in the collection of the first type of taxes is permissible, whereas working in the collection of the second type of taxes is not permissible, because it constitutes cooperation in sin and aggression.