If you're not sure of the rules, go find out the rules. Go to HR. If they don't know the answer, have them get you in touch with whoever designed the plan or the actuator or whoever, right? Somebody knows the answer to your question. It takes time for the benefit of the tax protective growth to overcome the benefit of paying at the lower long term capital gains rates on the gains. How much time will it depends? It depends on what fees are charged in the account, what you plan to invest in and your investment behavior.