Some doctors, and even their accountants, consider using the slightly simpler SEP-IRA instead, which has the same $55,000 total contribution limit. However, thanks to the employee contribution feature of an individual 401(k), you can hit the maximum contribution of $55,000 with a much lower income. In addition, using the 401(k) instead of a SEP-IRA allows you to do a backdoor Roth IRA since the balance of a SEP-IRA is included in the required pro-rata calculation (explained below) but the balance of a 401(k) is not.

Whether you are employed or self-employed, you can also contribute to a personal backdoor (indirect) Roth IRA and, if married and you have sufficient income, a spousal backdoor Roth IRA. These became permitted in 2010 when Congress began allowing high-earners to do Roth conversions. Instead of a direct Roth IRA contribution, you first contribute to a traditional IRA, which is not deductible due to your high income, and then move that money to a Roth IRA.

Since you never received a deduction, there is no tax cost for the conversion, and the end effect is the same as if you had contributed directly to a Roth IRA. Annual contribution limits are $5,500 if younger than age 50 and $6,500 if older than age 50. Be aware that due to the pro-rata rule, the conversion is only tax-free if you have no balance in a SEP-IRA, SIMPLE IRA, or traditional IRA on Dec. 31 of the year of the conversion. If you do have one of those accounts, you may wish to roll it into a 401(k), such as your new individual 401(k), to facilitate future backdoor Roth IRAs.

A health savings account (HSA) can also function as a stealth IRA and is an excellent account to use for retirement savings. Not only does it give you an upfront tax break and tax-protected growth like a 401(k), it also provides for tax-free withdrawals if the money is used for health care. This makes it the most tax-advantaged account available to the investor. These funds can be invested in mutual funds like a typical retirement account. The contribution limit for 2018 is $3,450 for individuals and $6,900 for families. If you end up not needing it for health care, you can withdraw the money penalty-free after age 65. However, you would need to pay taxes on that withdrawal, just like a 401(k).