The IRS refers to the Individual 401(k) as a one-participant 401(k). Also known as a Solo-k or Uni-k, the Individual 401(k) is the basic retirement account for the self-employed individual who has no employees.

Eligibility requirements

Individual 401(k) contribution limits

As a business owner, you are both an employEE as well as an employER of the business. So you get to contribute to the Solo 401(k) in both buckets.

The total you can contribute towards the plan, both buckets included, is $57,000 for 2020.

Employee Contribution

  1. As an employee of your own business, you get to contribute “Elective deferrals”. You can contribute up to 100% of your compensation, up to a maximum of $19,500 for 2020.

If you are 50 or older, you get a $6000 catch-up contribution. Both of these values are adjusted annually.

Please note, this is the maximum you can contribute as an employee towards all 401(k) plans that you may have access to. Say you also have an employed position, as a W-2 physician, and contribute to a 401(k) plan through your work there. Then you’ll get to contribute only the difference to make up the total to $19,500 towards your individual 401(k).

If you contribute $19,500 at your work 401(k), then you may not contribute any more towards your individual 401(k).

If you only contribute $10,000 at your work 401(k)- maybe to get an employer match- then you may contribute $9500 in your solo-k to make up the total to $19,500.

Employer Contribution

2. The second bucket is referred to as “non-elective contributions” or the “Profit Sharing” component. It is your contribution to the individual 401(k) as an employER.

Profit Sharing can range from 0-25% of plan compensation, but staying within total contribution limits. For 2020, if you are maxing out the employee contribution at $19,500, then the max you can put in for profit sharing is $57000-19,500= $37,500.

Plan compensation is defined by net earnings from self employment after deducting both:

So it’s a bit of a Catch-22. You need to know your compensation in order to calculate your contribution. And you need to know the contribution in order to figure out your compensation.

Trust the IRS to keep it simple.

Sole proprietor versus S corp

As a sole proprietor, you don’t pay yourself a W2. So your compensation is the same as net business profit reported on Schedule C, i.e., gross income minus business expenses.

Adjusted net business income = Net business income (-) 1/2 SE tax

Self Employment Tax includes Social Security Tax of 12.4% on the first $137,700 you make + 2.9% of Medicare Tax on your entire income.

0.9% Additional Medicare Tax on income more than $200,000 is not included among SE Tax.

You get to contribute 20% of adjusted net business income towards the Profit Sharing/employER portion of your Individual 401(k), as a sole proprietor.

If you elect file taxes as an S-corp, you take some of your compensation in the form of W-2 wages from your business. The rest you take as distributions. For purposes of contributions to the individual 401(k), only the W-2 wages count. The distributions do not.

And the employER contribution is a maximum of 25% of W2 compensation.

Online Calculators

I have found these calculators to be most helpful:

If you like math enough, IRS Pub. 506 has a worksheet for it.

Contribution Limits: Sole Proprietor versus S corp

If you play around with these calculators, you will find that at lower income levels, you get to contribute different amounts towards the profit sharing component, depending on whether you are a sole proprietor or an S corp.

For example, if you have $100,000 in net business income (gross income – expenses) as a sole proprietor, you are able to contribute a max of $18,587 towards profit sharing (20% of adjusted net business profit)

If you have the same $100,000 in S corp wages, you get to contribute $25,000 as profit sharing (25% of compensation).

We typically do not encounter this issue since most people do not elect to file as S corp with lower income.

Once income hits the level needed to max out 401(k) contributions, ie., $198,699 for 2020, this difference disappears.

The exact amount of contribution also depends on other income you have. Based on this, you may have maxed out Social Security Tax on your other wages and it may not apply to your self-employed income.

General characteristics of Individual 401(k) Plans

Other qualified plan options for the self-employed

Instead of an individual 401(k), you may choose to open a SEP IRA as your business retirement plan. The two downsides with this are:

Similarly, a SIMPLE IRA is also suboptimal because it lets you contribute a lot less than the Individual 401(k).

Where to Open an Individual 401(k)

I hope this is helpful. Please let me know if you have comments or questions below!

One Response

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.