The Affordable Care Act is not "the largest tax increase in the history of the world," despite what you might have heard on The Rush Limbaugh Show. In fact, it's not even the largest tax increase in the history of The Rush Limbaugh Show. Two years after Rush's national syndication, President George H. W. Bush signed a slightly bigger tax increase in 1990. And Reagan's tax increase from 1982 was bigger than both of them.
If you're looking for something/anything superlative to say about the ACA, you could say it's the biggest tax increase of the entire millennium (!!!) or perhaps that it's the second-biggest tax increase signed by a Democrat since LBJ. As for the biggest tax acts in "history," health care reform barely cracks the top ten ... for the last 60 years.