SEP & SIMPLE IRA Pro Rata Rule: Backdoor Roth

If you are self-employed and wondering whether the SEP SIMPLE IRA pro rata rule applies to your backdoor Roth, the short answer is yes: both a SEP IRA and a SIMPLE IRA count in the same aggregation pool as any traditional or rollover IRA. For freelancers and business owners, these employer-style IRAs are the accounts most likely to quietly make a Roth conversion taxable.

Yes: SEP and SIMPLE IRAs Both Count for the Pro-Rata Rule

Many self-employed savers assume a SEP or SIMPLE IRA sits in a separate bucket because it feels like a workplace plan. It does not. The tax code treats both as traditional IRAs for aggregation purposes, so their pre-tax balances are combined with any other traditional or rollover IRA when the pro-rata fraction is computed. For a backdoor Roth strategy, that combined balance is often the deciding factor in how much tax you owe.

Why a SEP IRA counts even though it feels like a work plan

A SEP IRA (Simplified Employee Pension) is funded with employer contributions, which is why it reads like a company plan. Legally, though, the assets live inside a traditional IRA. Contributions are pre-tax, growth is tax-deferred, and distributions are taxed as ordinary income, exactly like a garden-variety traditional IRA. Because the code makes no distinction, a SEP balance is folded into the pro-rata calculation dollar for dollar. A freelancer with a healthy SEP who tries a clean backdoor Roth is often surprised to find the conversion is mostly taxable.

Why a SIMPLE IRA counts too, including the 2-year nuance

A SIMPLE IRA (Savings Incentive Match Plan for Employees) is likewise a traditional IRA under the code, so it aggregates the same way. There is one extra wrinkle unique to SIMPLE plans: a 2-year seasoning period that starts on the date the first contribution is deposited into your SIMPLE IRA. During those two years, rolling SIMPLE money into a 401(k), the usual escape hatch discussed below, is not permitted, and an early distribution can trigger a 25 percent penalty instead of the standard 10 percent. The balance still counts for pro-rata purposes the entire time.

Which Accounts Count vs. Which Are Invisible to the Pro-Rata Rule

The pro-rata rule only sees certain accounts. It aggregates every traditional-flavored IRA you personally own, but it is blind to employer plans that are not IRAs and to Roth accounts. Knowing which balances land in the pool, and which do not, is the whole game when you are deciding whether a backdoor Roth is clean or costly. The table below sorts the common account types.

The pro-rata pool: Traditional, SEP, SIMPLE and Rollover IRAs

Under IRC section 408(d)(2), all of your traditional, SEP, SIMPLE and rollover IRAs are treated as one single IRA for the taxable-amount calculation. You cannot cherry-pick which dollars convert. Even if your $7,000 nondeductible contribution sits in its own brand-new account, the IRS blends it with every other pre-tax IRA dollar you hold.

What is excluded: 401(k), Solo 401(k), 403(b), 457(b) and Roth IRAs

Employer plans that are not IRAs are invisible to the calculation. A 401(k), Solo 401(k), 403(b) or 457(b) balance does not enter the pool, which is precisely why the reverse-rollover fix works. Roth IRAs are also excluded because they hold only after-tax money. This exclusion is the lever the self-employed can pull to keep a backdoor Roth clean.

The December 31 balance rule, not the conversion date

The pro-rata fraction uses your total IRA balance on December 31 of the conversion year, not the balance on the day you convert. This traps January contributors: someone who empties an IRA in March, converts in April, then rolls a SEP back in during November still has that balance counted on December 31. The timing that matters is year-end, a point many savers confirm against the 2026 Roth conversion deadline.

How the Tax Is Calculated on a SEP/SIMPLE-Owner’s Backdoor Roth

The tax turns on one fraction: how much of your total IRA money is after-tax basis versus pre-tax. When a large SEP or SIMPLE dwarfs a small nondeductible contribution, the after-tax slice is tiny, so nearly all of the conversion is taxed as ordinary income in the conversion year. Understanding the formula helps many savers estimate the bite before initiating a conversion.

The pro-rata formula

The tax-free percentage of any conversion equals your total after-tax basis divided by the total year-end (December 31) balance of all your traditional, SEP, SIMPLE and rollover IRAs combined. Everything left over is taxable ordinary income. Expressed simply:

• Tax-free fraction = after-tax basis / total year-end IRA balance
• Taxable fraction = 1 minus the tax-free fraction

Worked example: a freelancer with a $92,000 SEP

Consider an illustrative freelancer who holds $92,000 in a SEP IRA and makes a $7,000 nondeductible traditional IRA contribution intending to convert it. This is a hypothetical for education only and is not a projected result.

• Total year-end IRA balance: $92,000 plus $7,000 = $99,000
• After-tax basis: $7,000
• Tax-free fraction: 7,000 / 99,000 = about 7.1 percent
• Tax-free portion of the $7,000 conversion: about $495
• Taxable portion: about $6,505, roughly 92.9 percent of the conversion

So converting $7,000 that felt like after-tax money actually adds about $6,505 of ordinary income. At a 24 percent marginal rate that is roughly $1,561 of federal tax on a conversion the saver expected to be nearly tax-free. The leftover $6,505 of basis does not vanish: it stays tracked on Form 8606 and reduces tax on future conversions, but the pro-rata blending repeats every year the SEP remains funded. Modeling this against your bracket, as covered in how much to convert to Roth, is often more useful than a rule of thumb.

Form 8606: reporting basis and the taxable fraction

Form 8606 is where the whole calculation is documented. Nondeductible contributions are reported on Part I, which tracks your cumulative after-tax basis. The conversion and its taxable amount flow through Part II, where the pro-rata math produces the figure that lands on your Form 1040 as taxable income. Filing Form 8606 in every year you make nondeductible contributions is what preserves your basis; skipping it risks paying tax twice on the same dollars.

How the Self-Employed Can Empty the SEP or SIMPLE Before December 31

Because the pool is measured on December 31, the self-employed have a fix that most W-2 employees do not: moving the pre-tax IRA money into a plan that the rule cannot see. A Solo 401(k) is the usual vehicle. Done before year-end, it can reduce the taxable fraction of a backdoor Roth toward zero, though the SIMPLE 2-year rule and setup deadlines constrain the timing.

The Solo 401(k) reverse rollover

A Solo 401(k) (an owner-only 401(k)) is not an IRA, so any balance inside it is excluded from the pro-rata calculation. The “reverse rollover” moves your pre-tax SEP or traditional IRA dollars into the Solo 401(k). If your only remaining IRA balance on December 31 is the $7,000 of after-tax basis you intend to convert, the tax-free fraction approaches 100 percent and the backdoor Roth becomes nearly tax-free. Both the rollover and the establishment of the Solo 401(k) must be completed by December 31 of the conversion year, because that is the date the balances are measured.

The SIMPLE IRA 2-year rule that can block the rollover

If your pre-tax money sits in a SIMPLE IRA, the 2-year clock can stop this plan cold. The clock starts on the date of the first contribution to your SIMPLE IRA. Before two years elapse, SIMPLE funds generally cannot be rolled into a 401(k) or Solo 401(k), and a premature distribution can incur a 25 percent penalty on top of income tax. SEP IRAs carry no such seasoning restriction, so a SEP can typically be swept into a Solo 401(k) right away.

Alternatives if the reverse rollover is not available

When a Solo 401(k) rollover is off the table, other approaches exist. One is to convert the entire SEP to a Roth over several years, accepting the tax in exchange for eliminating the pro-rata drag permanently, an approach that pairs with a Roth conversion ladder for those with runway. Another is simply to set up the Solo 401(k) before year-end so the rollover window opens in time. A full multi-year conversion of an $80,000-plus SEP could take four or more years at a moderate bracket and cost thousands in tax, so many savers weigh it against the break-even horizon first.

When the backdoor Roth is not worth it

If the conversion is small relative to a large SEP and no Solo 401(k) fix is practical, the after-tax benefit of a $7,000 backdoor Roth may not justify triggering tax on the pro-rata slice each year. Some savers in that position pause the backdoor entirely, focus on direct Roth conversions from the SEP, or defer until they have wound down the pre-tax balance. There is no single right answer; the math depends on your bracket, timeline and cash to pay the tax.

Frequently asked questions

Does a SEP IRA count for the pro-rata rule?

Yes. A SEP IRA is a traditional IRA under the tax code, so its pre-tax balance is aggregated with all your other non-Roth IRAs when the pro-rata rule computes the taxable portion of a Roth conversion. Even though it is employer-funded and feels like a workplace plan, the IRS blends it into the same pool as any traditional IRA.

What is the exact pro-rata formula?

The tax-free fraction of a conversion equals your total after-tax basis divided by the total year-end (December 31) balance of all your traditional, SEP, SIMPLE and rollover IRAs combined. The taxable fraction is one minus that number. You multiply the taxable fraction by the amount converted to find the ordinary income added, which is reported on Form 8606.

Which date’s balance does the IRS use, the conversion date or December 31?

The IRS uses your combined IRA balance on December 31 of the conversion year, not the balance on the day you convert. This traps January contributors and anyone who moves money mid-year: emptying an IRA before converting does not help if a SEP or rollover balance reappears in the account by year-end, because December 31 is the only snapshot that counts.

Which accounts count in the pro-rata pool and which are excluded?

Counted: traditional IRAs, SEP IRAs, SIMPLE IRAs and rollover IRAs, including nondeductible contributions. Excluded: 401(k), Solo 401(k), 403(b), 457(b) plans and Roth IRAs. Inherited IRAs and a spouse’s IRAs are also outside your personal calculation. The exclusion of 401(k)-type plans is what makes the Solo 401(k) reverse rollover an effective fix.

What is the SIMPLE IRA 2-year rule?

The 2-year clock starts on the date of the first contribution to your SIMPLE IRA. Before it elapses, SIMPLE funds generally cannot be rolled into a 401(k) or Solo 401(k), and an early distribution can trigger a 25 percent penalty rather than the usual 10 percent. The balance still counts for pro-rata purposes throughout the seasoning period.

Under which IRC section is the aggregation rule found?

The IRA aggregation rule is codified at Internal Revenue Code section 408(d)(2). It directs that all of an individual’s non-Roth IRAs be treated as a single contract when determining how much of a distribution or conversion is taxable, which is why SEP and SIMPLE balances cannot be separated from a nondeductible contribution.

What are the 2026 backdoor Roth limits and Roth income phase-outs?

For 2026 the traditional IRA contribution limit being converted is $7,500, or $8,600 for those age 50 and older. Direct Roth contributions phase out at MAGI of $153,000 to $168,000 for single filers and $242,000 to $252,000 for married filing jointly, which is what pushes higher earners toward the backdoor. A Roth conversion itself has no income limit.

How does a Solo 401(k) reverse rollover eliminate the pro-rata bite?

Rolling pre-tax SEP or traditional IRA dollars into a Solo 401(k) removes them from the IRA pool the pro-rata rule measures. If the only IRA balance left on December 31 is your after-tax basis, the tax-free fraction approaches 100 percent. Both the rollover and the Solo 401(k) itself must be established by December 31 of the conversion year.

Does my spouse’s IRA count against my pro-rata calculation?

No. The pro-rata rule is applied per individual, and IRAs are never jointly owned. Your spouse’s traditional, SEP or SIMPLE IRA balances do not enter your calculation, and yours do not enter theirs. Each spouse runs a separate Form 8606, so one spouse can complete a clean backdoor Roth while the other cannot.

What is the cost of getting the pro-rata rule wrong?

Getting it wrong adds unexpected taxable ordinary income in the conversion year and can lead to double taxation when Form 8606 is not filed to track basis, since nondeductible basis in Part I and the taxable amount in Part II flow to Form 1040. A large pre-tax balance can also raise MAGI toward the net investment income tax thresholds, though a conversion is not itself net investment income, and required minimum distributions cannot be converted.