While a protocol as a whole, may be comprised of more than one header type that it uses for communication purposes to exchange information such as state and transmit application specific data. This is the reason why sometimes a protocol is described as a protocol suite.
Since January 1, 2006, U.S. employers have been allowed to amend their 401(k) plan document to allow employees to elect Roth IRA type tax treatment for a portion or all of their retirement plan contributions. The same change in law allowed Roth IRA type contributions to 403(b) retirement plans. Employees can roll their Roth 401(k) contributions over to a Roth IRA account upon termination of employment. 2  It is the employer's decision whether to provide access to the Roth 401(k) in addition to the traditional 401(k).
On a pretax basis, employees can't contribute above certain limits. In 2015, for instance, the limit is $18,000; those 50 and older can make additional catch-up contributions of $6,000. This money is not counted toward income, and all gains are tax-deferred.The limits are the same for Roth 401(k)s, though the contributions do count toward income and all gains are tax-free.But employees can sock away a lot more retirement cash if their company plan offers an after-tax option in a traditional 401(k). People who made after-tax contributions to their traditional 401(k) plans throughout the 1980s and 1990s, before the advent of the Roth IRA and Roth 401(k). 2  People who want to build up a Roth IRA with the goal of passing it on to heirs.