Nearly every educated financial advisor agrees that tax diversification is a great idea when planning for your distributions in retirement.  Tax diversification means having some of your assets in tax-deferred accounts (fully taxed upon withdrawal), some of your assets in Roth accounts (tax-free upon withdrawal), and some of your assets in taxable accounts (earnings taxed at lower long-term capital gains/dividend rates, or tax-free in the case of municipal bonds).  However, it can be very difficult to make recommendations as to what the ratio of one type of account to another should be.  Here are some thoughts on determining what you are aiming for.

Controlling Your Effective Tax Rate In Retirement

The point of tax diversification is to control how much tax you pay and when you pay it.  Consider a married retiree taking the standard deduction with a $1,000,000 traditional IRA and a $1,000,000 Roth IRA and no other source of income.  He figures he needs $75,000 in after-tax income to maintain his standard of living.  How much should he take from each account? There are an infinite number of combinations.  Here are a few:

  1. Take all the money from the traditional IRA and allow the Roth IRA to grow for heirs.  He would withdraw $83,585 and pay $6,770 in taxes, for an effective tax rate of 8.1%.
  2. Take all the money from the Roth IRA (this is only an option before age 70 1/2 when required minimum distributions must begin.)  He would withdraw $75,000 and pay $0 in taxes, for an effective tax rate of 0%.
  3. Take $20,300 from the traditional IRA and $54,700 from the Roth IRA.  He would withdraw $75,000, pay $0 in taxes, have an effective tax rate of 0%, lower future RMDs, and preserve $20K more in the tax-free Roth IRA.  Is it becoming clear yet why tax diversification is a good thing?
  4. Take $38,450 from the traditional IRA and $38,365 from the Roth IRA.  He would withdraw $76,815 and pay $1,815 in taxes, for an effective rate of 2.4%.
  5. Take the RMD from the traditional IRA (if he is 70, this is 1/27.4 or 3.65% of the balance of the account, or $36,500) and $40,120 from the Roth IRA and pay $1,620 in taxes for an effective rate of 2.1%.
  6. Take the maximum amount of income allowed without making your Social Security income taxable ($32,000 for married filing jointly) and $44,170 from the Roth IRA, for a total withdrawal of $76, 170, a total tax of $1,170 for an effective tax rate of 1.5%.

Take Home Points From That Exercise

I want you to notice a few take-home points from that exercise.

  1. The difference between your marginal tax rate now and your effective tax rate later on withdrawals from tax-deferred accounts can be dramatic.
  2. Having a Roth account of significant size in retirement gives you a ton of options and can lower your tax bill significantly.
  3. There are a lot of factors that go into this decision of how to withdraw from accounts of any given size, and these need to be considered when deciding the ratio of Tax-deferred to Roth to Taxable you are looking for in retirement.

Methods of Increasing Your Roth to Tax Deferred Ratio

There are several methods of increasing your Roth to Tax Deferred Ratio. One way that most physicians ought to be taking advantage of is to make a personal and spousal Backdoor Roth IRA contribution every year. Another way is to make Roth 401K and Roth 403B employee contributions instead of tax-deferred employee contributions.  This comes with the downside of raising your taxes while working, and probably raising your overall lifetime tax bill (at least when accounting for the time value of money.)

The Mega Backdoor Roth IRA is an option for a few.  Another great option is Roth conversions.  These can be best done in years when your taxable income is low, such as sabbaticals, deployments, while working part-time, while living in a low income-tax state, or after retirement but before taking Social Security.  Converting money at 0%, 10%, and 15% rather than later withdrawing it at 25% or more is obviously a smart move.

Don’t Forget State Taxes

State income taxes are also a factor to keep in mind.  The higher your state taxes, the worse of an idea making Roth contributions instead of tax-deferred contributions or doing Roth conversions may be.  If you’re working in New York City or California, but plan to retire to Florida or Texas, withdrawing tax-deferred contributions in retirement won’t be nearly as painful. If you plan to stay in your high-tax state in retirement, the arbitrage between your marginal tax rate while working and your effective tax rate in retirement is larger than for someone in a low-tax state.

The Taxable Account


Taxable accounts make these decisions even more complicated.  One of the most important factors is the basis on those investments. If your basis is high, you can “withdraw” a lot of money from your taxable account while paying a very low amount of taxes on that money.

For example, if you sell $50K in stock to spend in retirement, but the basis on that stock is $45K, then your tax bill on that money will be only $750 ($5K*0.15%) for an effective rate of just 1.5%. On the other hand, if the basis were just $5K, your tax bill would be $6,750, an effective rate of 13.5%.  This factor suggests that taxable account contributions should be less of a priority early in your career as compared to tax-protected accounts.

Current law provides for a better benefit for a taxable account.  If you can keep your marginal tax rate to 15% or less, your long-term capital gains and qualified dividend tax rate is just 5%.  So if your investments kicked out $10K in distributions, and you sold another $40K of stock with a basis of $20K, your taxes on that $50K could be as low as $1,500, for an effective tax rate of just 3%.  Possession of a taxable account of significant size is yet another reason to try to limit the size of tax-deferred account withdrawals in retirement.

Pensions, Individual Retirement Annuities, Income Property, and Working In Retirement

The largest benefits of using tax-deferred retirement accounts to save for retirement accrue to those who have no other income in retirement.  They can then use their withdrawals to “fill-up” the 0%, 10%, and 15% brackets.  However, if you have significant other taxable income from pensions, IRAs that you converted to a SPIA, paid-off investment properties (although this income can still be sheltered somewhat if you are still depreciating the property), or heaven forbid a job at Wal-Mart, this income will fill up those brackets.  If you made 401K contributions at a marginal rate of 33%, then later withdraw the money at an effective rate of 33%, your only benefit of using the account was the much smaller benefit of tax-deferred growth.

Social Security Taxation

One of the most troubling aspects of determining the ideal Roth to Tax-deferred to Taxable ratio is the phase-out range for Social Security taxation and its effects on your true marginal tax rate.  If you can keep your taxable income under $32,000/$25,000 (married filing jointly/single) then your Social Security benefits aren’t taxable at all.  If your income is over $44,000/32,000 (married filing jointly/single) then a maximum 85% of your Social Security benefits are taxable at your regular marginal tax rate.  Within this range, your marginal tax rate can be as high as 46%. Contributing money to a 401K at a 33% marginal rate, and withdrawing it at a 46% marginal rate is a losing formula if there ever was one.

Some Rules of Thumb

Obviously, this process is very complicated.  There simply is no rule of thumb of what percentage of your retirement assets should be in Roth, traditional, or taxable accounts.  However, here are some general guidelines for both the accumulation stage, and the distribution stage.

Accumulation Stage

  1. Residents should go Roth. Early in your career, such as during residency and fellowship, contribute preferentially to Roth accounts (Roth 401(k)s, Roth 403(b)s, and Roth IRAs.
  2. Max out your personal and spousal Backdoor Roth IRAs each year.  You are not comparing these to a tax-deferred account, but rather to a taxable one, and the Roth account is far superior to a taxable one, not only for the tax-protected growth, but also the tax-free withdrawals.
  3. Convert taxable + tax-deferred assets to Roth assets during low-income years. You don’t necessarily want to use tax-deferred money to pay the taxes on a Roth conversion, but if you have money from current earnings or a taxable account (especially with high basis) to pay the taxes, you can increase your Roth percentage without too high of a tax bill.
  4. Read your 401K document to see if a Mega Backdoor Roth IRA is an option for you.
  5. Roth money is better than tax-deferred money, but you generally don’t want to pass up opportunities during your peak earning years to contribute to tax-deferred accounts. Exceptions to this rule are noted in 6 and 7 below.
  6. If you expect to be in the top tax bracket in retirement, make Roth 401(k)/403(b) contributions preferentially, or take advantage of the Mega Backdoor Roth IRA variation using a SEP-IRA.
  7. Consider Roth 401(b)/403(b) contributions if you have a very low Roth to Tax-deferred ratio. The flexibility may be worth losing the tax arbitrage.
  8. If you expect significant taxable income in retirement (real estate investments, pensions etc), such that the lowest tax brackets will be filled before you get to your tax-deferred withdrawals, then make more Roth contributions and Roth conversions now.  If there is no tax arbitrage, Roth accounts are just as useful as tax-deferred accounts, and you can put a lot more money into them when considered on an after-tax basis.
  9. If you expect huge RMDs in retirement (the RMD is 5.3% at age 80) due to huge tax-deferred accounts, then start converting.  An orthodontist on Bogleheads recently noted his RMDs were larger than his salary when he was working.  I’m not sure if he adjusted for inflation, but you probably don’t want to end up with a traditional IRA larger than $2-3 Million in today’s dollars (RMD at 80 = $106K-159K.) Truly a first world problem, but the larger your retirement stash, the higher your Roth to tax-deferred ratio ought to be.
  10. Consider easing into retirement if possible with part-time work, allowing you a few years of lower earnings to increase your Roth to tax-deferred ratio using contributions and/or conversions.  Filling up the 10% and 15% brackets with Roth conversions is generally considered a smart move.
  11. Use proper asset location strategy to maximize the size of retirement accounts.  Although it is nice to have tax-inefficient assets in tax-protected accounts, you must also take into account the expected return of the asset when determining appropriate asset location. Putting high expected return assets preferentially into Roth accounts over tax-deferred accounts is really just taking on a more risky portfolio when considered on an after-tax basis, but it does serve to increase the likely Roth to tax-deferred ratio.
  12. Taxable accounts are better if the basis is high.  Contribute to taxable accounts only after the other accounts are already full. To suggest otherwise is generally bad advice.  It would be a very rare person who should preferentially contribute to a taxable account (at least for retirement purposes) instead of a tax-deferred one. It is easy to get to tax-protected money without penalty before age 59 1/2.

Distribution Stage

  1. Delay Social Security to age 70 (although if married, the lower-earning spouse should take theirs earlier). Aside from the obviously larger payments and better longevity insurance, this allows you some years between retirement and receiving Social Security to do some Roth conversions. Filling up the 10% and 15% brackets with Roth conversions is generally considered a smart move.
  2. Determine how close you will be to the Social Security taxation range.  If you’re way over, no big deal.  If you’re easily under, good for you (although it might not be that comfortable of a retirement.) If you are anywhere near that range, a careful withdrawal strategy is critical to avoid ridiculously high marginal rates.
  3. There isn’t much you can do about RMDs once you hit age 70 1/2.  That will be your minimum tax-deferred withdrawal.  Might as well pay your taxes and spend them.  Only if you have a very high ratio of tax-deferred to Roth and taxable accounts do you need to consider taking your RMDs and investing them in a taxable account to ensure you don’t run out of money.
  4. Use your Roth IRA to keep you in a lower bracket.  Try to fill the 0%, 10%, 15%, and (depending on the level of assets) even the 25% bracket using tax-deferred money.  Any additional money needed above that can come from the Roth.
  5. Taxable accounts can also be used to keep you in a lower bracket. 
  6. Spend the taxable assets with high basis first. Not only does it lower your tax bill, but it maximizes the benefit of the step-up in basis at your death.
  7. Your heirs will prefer a Roth IRA to a taxable account and a taxable account to a traditional IRA.  That said, if your heirs are poor, the overall tax burden may be lower if they pay the taxes on traditional IRA instead of you. Besides, beggars can’t be choosers.  They should be grateful for whatever you leave them.
  8. Charities, however, are perfectly fine with a traditional IRA.  They don’t pay taxes anyway.  So when doing estate planning, leave the Roth and the taxable to the kids, and use the traditional IRA for any charitable bequests. If you wish to maximize the amount left to kids, spend the tax-deferred money.  If you wish to maximize the amount left to charity, spend the Roth and taxable money.

I hope those 20 rules are helpful to you in deciding how to acquire maximal tax diversification in retirement, without paying unnecessary taxes now.  What do you think?  Did I miss anything?  Any questions?  Comment below!