Affiliated Title Is Federal Income Tax Mandatory To Pay? What Are The Consequences?

Is Federal Income Tax mandatory to pay? What are the consequences? - affiliated title

I saw a documentary called Zeitgeist and there is talk that the Fed is not with the federal government on income and taxes related actually are unconstitutional. If so, why are we obligated to pay and what if they do not. I'm sure it's a question of age, but I think the law of economy and society do not know much. I would be glad to help, thank you!