Can a participant elect to convert pre-tax 401(k) deferrals into Roth 401(k) deferrals?
No. The regulations make it very clear that when a participant elects to make pre-tax deferrals, that election is irrevocable. While the participant may change how future contributions are designated, existing contributions cannot be converted within the plan. However, there has been discussion on Capitol Hill about changing the law to allow conversions inside the 401(k) plan similar to the IRA conversions that are allowed beginning in 2010.
