<prompt> Human: A coworker of mine just told me how he pays taxes. He declines to pay taxes from his paycheck gets 100 of it, then immediately deposits 30 into savings or a mutual fund, and pays his taxes at the end of the year. Of course, that principal would grow over the course of a year and you could pocket the return.Is this a smart idea, assuming your taxes are relatively straight-forward? How low-risk of a fund would you want in order to make this safe?  <response>: Eventually your friends employer will get a notice instructing them to withhold at a certain rate. 