It used to be official IRS policy to ignore people who made ridiculous claims about taxes being voluntary. However, they finally realized that their silence on the subject just fed into the hands of the promoters of such tax scams who used that as a sign that what they were saying must have been true.
As announced in this press release, IRS has just updated their guide to many of these tax scams, The Truth About Frivolous Tax Arguments, which can be seen on their website and downloaded as a 62 page pdf.
I had an interesting email conversation with a tax protestor a few months who was spouting some of these idiotic reasons why nobody has to file a tax return. After I finish the rest of our April 15 extensions, I will post it here on my blog.