|IRS 1040 form (irs.gov)|
Don't hear too many people cheering though! Probably the best headline I've read so far on this anniversary is, "Many Unhappy Returns." But, however one feels about the whole idea, it's a power that Congress was given when the 16th Amendment to the Constitution was ratified a hundred years ago. Cornell University Law School has a great legal website which provides a lot of info on the law and government. Here's their page on Amendment XVI.