As long as this is the rules of the country and you would be prosecuted if you don’t pay, you must pay it. But if it is cash and no one would know about it and there is no way that they can hold you accountable for it, you don’t have to pay it.

Is paying work tax obligatory in islam? If one has two jobs one where he has to pay tax and the other which is cash in hand and for this one he doesn’t is this permissible?