Backdoor Roth IRA for High-Income Business Owners

By Yarik Yarosh, CPA ·September 5, 2026 ·6 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

The Roth IRA is one of the most tax-efficient retirement accounts because qualified withdrawals are completely tax-free. But direct Roth IRA contributions are phased out for high-income earners: single filers with MAGI above $161,000 and married filing jointly above $240,000 can’t contribute directly. The backdoor Roth IRA strategy provides a legal workaround that allows high-income business owners to fund a Roth IRA regardless of income level.

✓Key takeaway

Backdoor Roth IRA mechanics:

Step 1: Contribute to a traditional IRA.

Contribute up to $7,000 ($8,000 if age 50+) to a traditional IRA
The contribution is nondeductible (the owner’s income is too high for a deductible traditional IRA contribution if they’re covered by an employer plan)
File Form 8606 to report the nondeductible contribution

Step 2: Convert the traditional IRA to a Roth IRA.

Convert the entire traditional IRA balance to a Roth IRA
If the traditional IRA only contains the nondeductible contribution: the conversion is tax-free (no taxable income because the contribution was already after-tax)
If the traditional IRA contains other pre-tax funds: the pro-rata rule applies (see below)

Step 3: File Form 8606.

Report the conversion on Form 8606
Track the basis (nondeductible contributions) and the taxable portion of the conversion

The pro-rata rule (the trap): If the owner has ANY pre-tax money in ANY traditional IRA (including SEP-IRA and SIMPLE IRA balances), the conversion is partially taxable. The IRS treats ALL traditional IRAs as one account for pro-rata purposes.

Example: the owner has $100,000 in a SEP-IRA (pre-tax) and makes a $7,000 nondeductible traditional IRA contribution. Total traditional IRA balance: $107,000. Nondeductible basis: $7,000 (6.5%). When the owner converts $7,000 to Roth: 6.5% is tax-free ($455), and 93.5% is taxable ($6,545).

How to avoid the pro-rata rule:

Roll existing IRA balances into a 401(k). A Solo 401(k) or employer 401(k) can accept incoming rollovers from traditional/SEP/SIMPLE IRAs. Once the pre-tax money is in the 401(k), the traditional IRA has a $0 balance (before the new contribution), and the backdoor conversion is tax-free.
Use a SEP-IRA that has been rolled into a 401(k). S-Corp owners with a Solo 401(k) should roll any existing SEP-IRA balance into the Solo 401(k) before executing the backdoor Roth.
Convert the entire traditional IRA balance. If the total is small enough (e.g., $20,000), pay the tax on the conversion and eliminate the pro-rata issue permanently.

Mega backdoor Roth (for Solo 401(k) owners): If the Solo 401(k) plan allows after-tax employee contributions and in-plan Roth conversions:

After maxing out the pre-tax deferral ($23,500) and employer contribution (up to 25% of compensation), contribute additional after-tax dollars up to the $70,000 combined limit
Immediately convert the after-tax contributions to Roth within the plan
This can shelter an additional $20,000-$46,500/year in Roth dollars
Not all plan documents allow this; the Solo 401(k) plan must explicitly permit after-tax contributions and in-plan conversions

How much does the backdoor Roth save over a career?

Hypothetical example

Round numbers. For current guidance, see IRS IRA contribution limits. A business owner, age 40, AGI $250,000 (above the Roth income limit). Contributes $7,000/year via backdoor Roth for 25 years (to age 65).

Total contributions over 25 years: $175,000

Roth IRA balance at age 65 (7% average annual return): $175,000 grows to approximately $475,000.

Tax savings in retirement:

The $475,000 is withdrawn TAX-FREE in retirement
If the owner would have been in the 24% bracket in retirement: $475,000 x 24% = $114,000 in lifetime tax savings
Plus: no required minimum distributions (RMDs) during the owner’s lifetime
Plus: the Roth IRA passes to heirs income-tax-free (though heirs must withdraw within 10 years under the SECURE Act)

Compared to taxable investment account: If the same $7,000/year were invested in a taxable account:

Annual dividends and capital gains distributions are taxable each year
At 2% annual dividend yield, 24% tax: approximately $2,280 in tax drag over 25 years
Upon withdrawal: long-term capital gains tax (15-20%) on the $300,000 in gains = $45,000-$60,000
Total tax on the taxable account: approximately $47,280-$62,280 over the life of the account

Backdoor Roth saves: approximately $47,000-$62,000 over a career compared to a taxable investment account with the same contributions.

Pro-rata calculation if the owner has a $200,000 SEP-IRA:

Total IRA balance after $7,000 contribution: $207,000
Nondeductible basis: $7,000 (3.4%)
Taxable portion of $7,000 conversion: $6,762
Tax on conversion: $6,762 x 24% = $1,623

To eliminate this: roll the $200,000 SEP-IRA into the Solo 401(k) before making the traditional IRA contribution. After the rollover, the traditional IRA balance is $0, the $7,000 contribution is 100% basis, and the conversion is 100% tax-free.

Timeline:

January: roll SEP-IRA into Solo 401(k) (takes 2-4 weeks)
February: confirm traditional IRA balance is $0
March: contribute $7,000 to traditional IRA (nondeductible)
April: convert traditional IRA to Roth (immediately, to avoid any investment gains in the traditional IRA)
At tax time: file Form 8606

Illustrative numbers only, not a real client and not advice for your facts.

Which retirement plan allows the highest contribution for a self-employed business owner?

A solo 401(k) or a defined benefit plan typically allows the largest contributions. A solo 401(k) allows up to $23,000 in employee deferrals ($30,500 if age 50+) plus an employer profit-sharing contribution of up to 25% of net self-employment income, for a combined maximum of $69,000 ($76,500 if 50+) in 2024. A SEP-IRA allows employer contributions of up to 25% of net self-employment income (after the self-employment tax deduction), maxing at $69,000. A cash balance or other defined benefit plan can allow contributions exceeding $200,000 per year depending on your age and plan design, making it the best option for high-income business owners over 50. All contributions reduce ordinary income dollar for dollar, though they don’t reduce self-employment tax.

What is the difference between traditional and Roth contributions to a solo 401(k)?

Traditional contributions are tax-deductible now, reducing your current-year taxable income, but withdrawals in retirement are taxed as ordinary income. Roth contributions are made with after-tax dollars (no current deduction), but qualified withdrawals in retirement are completely tax-free. The employee deferral portion ($23,000 in 2024, $30,500 if 50+) can be either traditional or Roth. The employer profit-sharing contribution (up to 25% of compensation) must always be traditional pre-tax. Roth contributions are advantageous if you expect your tax rate to be higher in retirement than it is now. Many solo 401(k) providers now offer both options, but you must specifically elect a plan that permits Roth contributions.

Related guides:

Backdoor Roth IRA for Business Owners: Step-by-Step Process and the Pro Rata Rule Trap

What are the catch-up contribution rules for business owners over 50?

Business owners aged 50 and older can make additional catch-up contributions beyond the standard limits for most qualified retirement plans. For 401(k) plans including solo 401(k)s, the catch-up contribution is an additional $7,500 for 2025 on top of the standard $23,500 employee deferral limit. SEP IRAs don’t have catch-up provisions because contributions are employer-only and already allow up to 25% of compensation or $70,000. SIMPLE IRAs permit a $3,500 catch-up for those 50 and older, and starting in 2025, participants aged 60-63 get an enhanced catch-up of $5,000 under the SECURE 2.0 Act.

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Cite this page

Yarik Yarosh, CPA. "Backdoor Roth IRA for High-Income Business Owners." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-backdoor-roth-ira-guide

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.