The Power of Tax-Deferred Growth Why are 401(k) plans, annuities, and IRAs so popular? Share | Related Content Social Security: By the Numbers Here are five facts about Social Security that might surprise you. What Is a Roth 401(k)? Roth 401(k) plans combine features of traditional 401(k) plans with those of a Roth IRA. Retirement Plan Distributions There are a number of ways to withdraw money from a qualified retirement plan.