We hear a lot about diversifying across asset classes — owning stocks, bonds, real estate, etc. We also hear a lot about diversifying within asset classes — owning mutual funds of hundreds of stocks rather than owning a few individual stocks. But there’s another, lesser-known form of diversification from which you could benefit: Tax diversification.
Tax diversification is the strategy of spreading your investments out across each of the different types of accounts:
When deciding between tax-deferred accounts or tax-free accounts, you’re answering the question “Do I want to be taxed on this now, or would I rather be taxed on this later?” In its simplest form, the decision comes down to how your current tax bracket compares to the tax bracket you expect to be in when you withdraw the money.
The first and most obvious reason for tax diversifying is that it’s impossible to know precisely what your tax rate will be in retirement, especially if retirement is still many years away. Based on current tax rates you may be able to say that your retirement tax bracket will be lower than your current one. But who’s to say that tax rates won’t change?
By spreading your investments across both tax-deferred and tax-free accounts, you can minimize the risk that you’ll be caught off guard by a significant change in tax rates. The second reason it pays to tax diversify is simple math: Putting all of your investments in either tax-free accounts or tax-deferred accounts is unlikely to be the most tax-efficient strategy.
For example, imagine an extreme scenario in which an investor has all of his retirement savings in a Roth IRA. Once he retires, none of his withdrawals would be taxable. At first glance, this may sound wonderful, but it’s really a huge waste.
If the investor had forgone some of his Roth contributions in order to contribute to a 401(k) or traditional IRA, he would have increased his taxable income in his low tax bracket years in exchange for reducing his taxable income during his high tax bracket years. That sounds like a good trade-off to me.
Because of all the variables involved, there’s no way to know precisely which breakdown of tax-deferred, tax-free, and taxable accounts is best. The strategy I suggest for most investors is to allocate their investment dollars in the following order:
This way you’ll be taking advantage of your employer-provided match, taking advantage of the low-cost investment options in an IRA (as compared to the high-cost funds frequently offered in a 401k), and achieving tax diversification all at once.
Mike Piper is the author of Investing Made Simple: Index Fund Investing and ETF Investing Explained in 100 Pages or Less. The book explained the following in plain-English with no technical jargon:


What is your advice for those that don’t qualify for a Roth? This means they are in a high tax bracket so do you skip that step and go right to taxable investments?
Also, when you mention maxing out a 401k should that be the traditional portion or the Roth portion?
Hi EoW: As to your second question, my experience is that most investors still don’t have a Roth option in their 401k. If they do, then what I’d suggest depends upon their income level (and whether they’re eligible for deductible traditional IRA contributions, Roth contributions, or neither).
Though I suppose in most cases my answer could be summed up as “do some of each.” Brilliantly sophisticated, isn’t it?
As to the question of people who don’t qualify for a Roth, my suggestions at that point would depend in large part upon their goals. (For example, a low-cost variable annuity can provide for a decent method of tax-deferred growth. But to the extent that leaving money to heirs is a priority for the investor, annuities begin to make less sense.)
Or, depending upon circumstances, the “backdoor” method into a Roth (via contributing to a nondeductible IRA, then converting it in 2010 into a Roth) can potentially make sense. But, as far as I can tell, the desirability of that strategy depends upon the investor’s current income level, projected retirement income level, and existing value of investments in tax-deferred accounts.
In short, my answers are:
1) It depends, and
2) This is a circumstance in which a well-informed accountant/financial planner can provide a lot of value.
To add a little teeth to this argument, take a quick look at historical top marginal tax rates at http://www.truthandpolitics.org/top-rates.php. Ed Slott has made a fortune out of tax diversification (he’s a bit on the extreme side of things), but this post is very solid in the advice of ordering retirement contributions by tax buckets.
Hi Michael.
Thanks for the link re: historical top marginal tax brackets, that’s some pretty interesting information.
As to Ed Slott, I’ve been meaning to pick up a book by him. Any suggestions as to a particularly good one? Or should I probably just go with the most recent?
I would start with ‘Your Complete Retirement Planning Roadmap’ or ‘Stay Rich for Life’ depending on how much depth you’re looking for. He’s hard to watch on the tele, but there can be no doubt that he knows his stuff inside and out. Either of these books are great reads for anyone who is getting serious about retirement planning. If you like the dirty details, go with the former, if you like a little more spin, go with the latter.
Excellent. Thank you for the suggestions.