I explicitly have them withhold way more than is necessary so that I'm assured that I don't have to pay up at the end (beginning?) of the year. It was especially nice this year, since my income suddenly became one-seventh what it was halfway through the year. And honestly, that $2000 would have gone unnoticed as $38 a week, but it's neat to get it all at once, despite the fact that, this year, it'll be going to pay for insurance, heating, and food instead of a toy.