While 401(k) retirement plans offer valuable tax deferral, Roth 401(k)s can be tax-free. With the latter, all distributions avoid income tax five years after your first contribution, if you're at least 59-1/2. The new tax law makes it easier to switch to a Roth 401(k), effective Jan. 1, 2013. Now, anyone can convert 401(k) funds to a Roth version, at any time. Before, you had to be eligible for a distribution, usually by reaching a certain age or