nostr:npub1kwn28smd86n22h93pn3eyn8r5d3tkpfvgy8jf8zt99wkkckyl7jsgncfut A SCOTUS ruling from roughly 70 years or so ago stated that just compensation for services rendered was not a profit and therefore not taxable. Taxable income includes profits as well as money earned from certain offices and licenses held, not wages, salaries, or tips.

Yea they are mandatory see: The 16th Amendment.