Should I Put Stocks in My Roth IRA and Bonds in My Traditional IRA?

A reader writes in, asking:

“If I have a Roth IRA and traditional IRA, is it better to put my stock funds in the Roth and the bond funds in the traditional IRA? That seems preferable, because as long as stocks do earn more than bonds it would leave me with more money down the road because the Roth is tax-free.”

Yes, it is often preferable to put your investments with higher expected returns in Roth accounts rather than tax-deferred accounts — but not for the reason you mentioned.

Loading up your Roth accounts (as opposed to tax-deferred accounts) with investments with higher expected returns will (assuming “expectations” pan out) leave you with more money to spend after taxes than if you had taken a different approach. But that’s simply because you took on more risk.

By putting your high-risk investments in a Roth, you expose yourself to more risk than you would if you had an equal allocation in both tax-deferred and Roth. The reason for this is that you feel the full effect of fluctuations in the balance of your Roth IRA, whereas you only feel a portion of the effect of fluctuations in the balance of tax-deferred accounts.

For example, imagine that you expect to have a marginal tax rate of 25% during retirement. If your Roth IRA’s value changes by $20,000, that changes the amount of money you have available to spend by $20,000. In contrast, if your traditional IRA’s value changes by $20,000, the amount of money you have available to spend only changes by $15,000 (because $20,000 in the traditional IRA is only worth $15,000 to you, given a 25% marginal tax rate).

In other words, using your Roth IRA entirely for high-risk investments is very similar to just bumping up your allocation to high-risk investments in the first place — it will likely result in more money in the end, but at the cost of higher risk.

Now, having said that, it does typically make sense to prefer to use the Roth for investments with higher expected returns.

Why?

Because Roth IRAs Have No RMDs

As long as a Roth IRA is owned by its original owner (as opposed to being owned by a beneficiary after the death of the original owner), RMDs do not have to be taken from the account at any point.

So, in that sense, you would prefer to have a Roth IRA of a given size rather than a proportionally-larger traditional IRA, because the Roth gives you better control over your money.

For example, you would rather have $75,000 in a Roth IRA than $100,000 in a traditional IRA with a 25% marginal tax rate, despite the fact that the two amounts are functionally equivalent in terms of how much they leave you with after taxes.

For that reason, it does typically make sense to use your Roth accounts for the investments with the highest expected return. But you should be aware that in doing so, you increase your overall risk, so you may want to compensate by reducing risk slightly in some other manner.