In general, we find that if you plan to retire earlier in life and take distributions later, then tilting more toward a Roth retirement account is beneficial.

For instance, if you had your retirement accounts weighted more heavily toward Roth accounts and retired at 65, yet waited to start withdrawing at 75, your final retirement balance at 85 would be $2.88 million under the simulations we used. If you were balanced across retirement accounts (50-50 split between accounts) your balance at 85 would be $2.8 million; if you weighted your holdings toward traditional retirement accounts, your balance at 85 would be $2.75 million.

On the other end of the spectrum, if you plan to retire later in life and take money out later in life, then aiming for a 50-50 split is best.