Which qualified retirement plan allows contributions after age 70 without mandatory distributions?

The correct answer is Roth IRA because this type of retirement account uniquely allows individuals to continue making contributions regardless of age, provided they have earned income. Unlike other retirement plans, a Roth IRA does not have age-related contribution limits, even after reaching 70 years old.

Additionally, Roth IRAs are distinguished by their treatment of distributions. While traditional IRAs and other qualified plans require minimum distributions starting at age 72, Roth IRAs do not require withdrawals during the owner's lifetime, which enables the funds to continue growing tax-free for a longer period.

The other options have specific age-related constraints or mandatory distributions that negate their suitability in this context. Traditional IRAs, for instance, require minimum distributions starting at age 72, and although 401(k) plans also have similar requirements, they do not allow for contributions past age 70 if you're no longer working. Simplified Employee Pensions (SEPs) also follow the same mandatory distribution rules as traditional IRAs and do not permit contributions after reaching 70½. Thus, the unique structure of Roth IRAs makes them the only option that permits contributions past the age of 70 without the burden of required minimum distributions.