A 401(k) can be an effective retirement tool. As of January 2006, there is a new type of 401(k) -- the Roth 401(k). The Roth 401(k) allows contributions to a 401(k) account on an after-tax basis -- with no taxes on qualifying distributions when the money is withdrawn. For some investors, this could prove to be a better option than the traditional 401(k), where deposits are made on a pre-tax basis but are subject to taxes when the money is withdrawn. Use this 401(k) or Roth calculator to help determine the best option for retirement.