Given a question on how an Islamic state handles tax, I'm sure some people are wondering: does Islam permit tax evasion?
Tax evasion refers to "trying to get out of paying tax that you rightfully owe, wherever you live." For example, if you earn $50k and get $10k in gifts, depending on where you live, you may be required to claim that $10k as income and pay taxes to the government. Tax evasion here would be to avoid declaring that amount in order to avoid paying tax on it.
Also to clarify, this question is about Muslims living in a Muslim or non-Muslim country where taxes are collected by law. Not an Islamic state (which doesn't exist).