What is the definition of illegitimate taxes, does this apply to income tax imposed on the wealthy, and what is the ruling on technical work within the apparatus for collecting it?

It is permissible for the state to impose taxes to provide essential services, provided that the public treasury has been depleted. However, imposing them without a corresponding benefit or while the public treasury is sufficient is religiously forbidden, and the one who collects them is considered not to enter Paradise, as stated in the hadith: "The collector of an unjust tax shall not enter Paradise." The permissibility of taxes is also conditional on there being no waste or misuse of public funds.