SEP IRA vs Solo 401(k): Best Retirement Plan for 1099 CRNAs

Most 1099 CRNAs do not have an investment problem.

They have a retirement-plan structure problem.

And no, this is not a retirement-plan PhD seminar. Nobody needs that. This is about choosing the bucket that lets a high-earning 1099 CRNA keep more options open.

Too many CRNAs either default to a SEP IRA because it sounds easy, or they ignore the retirement-plan decision until the CPA asks in March. That is the financial equivalent of intubating with a flashlight app.

A SEP IRA can be a perfectly reasonable tool. It is simple, flexible, and easy to understand.

But for many solo 1099 and locum CRNAs with no non-owner employees, the question should not be:

The better question is:

Because for the right CRNA, the Solo 401(k) may offer more flexibility, more contribution options, better Roth planning, and the potential for advanced strategies like the mega backdoor Roth.

Watch the video: SEP IRA or Solo 401(k) for 1099 CRNAs?

In this video, I walk through the major retirement-plan choices for 1099 and locum CRNAs: Traditional IRAs, Roth IRAs, SIMPLE IRAs, SEP IRAs, Solo 401(k)s, Roth buckets, after-tax contributions, and the mega backdoor Roth concept.

The big idea: contribution capacity is strategy

Most 1099 retirement mistakes do not happen because someone picked a bad investment.

They happen because the account structure was too small, too rigid, or set up too late.

A retirement plan is not just an account. It is a tax wrapper, a contribution formula, a payroll decision, and a paperwork system wearing a trench coat.

Translation: design first, investments second.

Your mutual fund or ETF matters. But the account container determines how much can get into the game, what tax treatment is available, and how much flexibility you may have later.

In CRNA terms: the drug matters, but the airway matters first. Same idea here. Contribution room is the airway.

First, understand the three tax buckets

Before comparing a SEP IRA to a Solo 401(k), you need to understand the three contribution types people constantly mix up.

The self-employed retirement-plan menu

For 1099 CRNAs, the main business retirement-plan menu usually includes:

• SIMPLE IRA
• SEP IRA
• Solo 401(k)

All three can work. Only one usually gives a high-income solo CRNA the most control.

SIMPLE IRA: the starter plan

A SIMPLE IRA can make sense for small businesses that want low administration and modest contribution goals.

It is not bad. It is just usually too small for the CRNA who is trying to build serious retirement-plan flexibility.

Simple is nice, but simple can be too small.

SEP IRA: the easy button, but not the power tool

The SEP IRA is popular for a reason.

• It is easy to establish.
• It is relatively easy to maintain.
• It allows flexible annual funding.
• It can often be set up by the tax filing deadline, including extensions.

That is why many CPAs default to it.

But for high-income 1099 CRNAs, the SEP IRA can fall short.

• No employee deferral bucket.
• No age-50 catch-up contribution.
• No Roth employee deferral framework.
• No voluntary after-tax 401(k) bucket.
• No built-in mega backdoor Roth design.
• Pre-tax SEP IRA balances can complicate backdoor Roth IRA planning.

Plain English: the SEP is simple, but it gives away control.

Solo 401(k): the one-person 401(k) wrapper

The Solo 401(k) is often the plan to beat for a solo high-income 1099 CRNA with no non-owner employees.

Why? Because the owner wears two hats.

• Employee hat: elective deferrals, which may be pre-tax or Roth if the plan allows it.
• Employer hat: employer profit-sharing contributions.
• Plan design hat: possible Roth deferrals, roll-ins, loans, and voluntary after-tax contributions if the document allows them.

If SEP is the easy button, Solo 401(k) is the control panel.

It is not always simpler. It is usually better engineered.

SEP IRA vs Solo 401(k): the practical comparison

Why the Solo 401(k) usually wins for 1099 CRNAs

I am careful with the word “usually.” This is not universal. Employees, affiliated businesses, payroll, entity structure, plan costs, and administration all matter.

But for the typical solo 1099 CRNA with strong income and no non-owner employees, the Solo 401(k) is usually the retirement plan I want you to understand before you pick anything else.

1. More ways in

A Solo 401(k) may allow employee deferrals, employer contributions, and possible after-tax contributions.

2. More tax flavors

Pre-tax, Roth, and after-tax-to-Roth options may be able to coexist inside the same plan design.

3. Cleaner Roth planning

Some Solo 401(k) documents may accept roll-ins from pre-tax IRAs. That can help reduce IRA pro-rata headaches for backdoor Roth IRA planning.

4. Better with W-2 plus 1099 income

This is a big one for locum CRNAs.

You do not get a second employee deferral limit just because you have a second job. The employee deferral limit is personal.

But maxing out a hospital 401(k) or 403(b) does not automatically kill the 1099 retirement strategy.

If the employers are unrelated and the rules line up, the 1099 Solo 401(k) may still create employer contribution room, and sometimes after-tax room.

That is not DIY territory when multiple entities, spouse businesses, employees, or ownership ties are involved. Controlled group and affiliated service group rules can change the analysis.

The plan document matters more than the sales page

Do not just ask, “Do you offer a Solo 401(k)?”

Ask:

A basic brokerage Solo 401(k) and a custom Solo 401(k) are not always the same animal.

Buying “a car” does not tell you whether it has all-wheel drive, heated seats, or a functioning cup holder. Same idea here.

If you want Roth flexibility or mega backdoor Roth potential, the document needs the right features.

• Roth employee deferrals
• Voluntary after-tax contributions
• In-plan Roth conversion or in-service distribution
• Roll-ins from pre-tax IRAs
• Form 5500-EZ readiness when the plan gets large enough

If the plan document does not allow the feature, you do not have the strategy.

You have a nice login screen and a future apology letter.

Mega backdoor Roth: the plain-English version

The mega backdoor Roth is not a secret account.

It is a strategy that depends on plan design, paperwork, and execution.

1. Contribute after-tax. Fill unused annual additions space with voluntary after-tax dollars, if the plan allows it.
2. Convert quickly. Move those dollars to Roth through an allowed in-plan Roth conversion or in-service rollover mechanism.
3. Grow Roth. Future qualified Roth growth may be tax-free, assuming all applicable rules are satisfied.

The trick is not “secret.”

The trick is paperwork plus plan design plus execution.

Where smart CRNAs mess this up

This is not a “rah-rah Solo 401(k)” post.

A great strategy can still fail if the administration is sloppy.

Picking the SEP IRA by default

The SEP IRA may be fine. But do not pick it just because it was easy to open in March.

Using the wrong Solo 401(k)

A basic plan document may not allow Roth deferrals, after-tax contributions, or Roth conversion.

Forgetting payroll realities

For S-corp CRNAs, retirement-plan contributions are tied to W-2 compensation. K-1 profit does not magically become retirement-plan compensation.

The answer is planning, not vibes.

Ignoring employees

A Solo 401(k) works cleanly when the business has no non-owner employees other than a spouse. Once employees enter the picture, you may need broader plan design, testing, safe harbor help, or a third-party administrator.

Missing annual filings

A one-participant 401(k) generally has filing requirements once plan assets reach the applicable threshold.

That is not a reason to avoid the plan. It is a reason to stay organized.

A practical decision guide

This does not replace advice. But it gives you a better first question than, “What account can I open before my CPA files the return?”

30-day implementation checklist

The right plan chosen in January is easier than the perfect plan discovered on December 27.

1. Confirm the facts.
   Entity type, employees, spouse involvement, W-2 plans, IRA balances, business income, and payroll setup.
2. Pick the plan design.
   Basic Solo 401(k), custom Solo 401(k), SEP IRA, SIMPLE IRA, or another plan structure depending on your facts.
3. Coordinate payroll and tax.
   Especially for S-corps: salary, deferrals, W-2 reporting, employer contributions, and deductions all need coordination.
4. Set the funding cadence.
   Monthly or quarterly systems usually beat December heroics.
5. Document and report.
   Track basis, conversions, 1099-Rs, plan balances, and annual filing obligations when applicable.

The three takeaways

1. After-tax is not Roth.

It only becomes powerful when the plan allows conversion.

2. SEP is easy, but easy can be expensive.

It may leave contribution room and Roth flexibility on the table.

3. Solo 401(k) is usually the best starting point.

For a solo high-income 1099 CRNA, it is usually the most flexible plan to evaluate first.

You do not need a more complicated life.

You need the right container.

Official references

• IRS: COLA increases for retirement-plan dollar limitations
• IRS: 401(k) limit increases to $24,500 for 2026; IRA limit increases to $7,500
• IRS: 401(k) and profit-sharing plan contribution limits
• IRS: One-Participant 401(k) Plans
• IRS: Designated Roth Account FAQs
• IRS: Rollovers of after-tax contributions in retirement plans