There's a very clear distinction: one is illegal, the other is legal. If you say someone is engaging in tax evasion, you're accusing them of a crime. If you say

There's a very clear distinction: one is illegal, the other is legal. If you say someone is engaging in tax evasion, you're accusing them of a crime. If you say someone is engaging in tax avoidance, you're accusing them of following the tax code as written. I am not a native speaker, tax mitigation seems to be the correct term that I should have used instead of tax evasion.