Convert SEP IRA to Roth IRA: Tax Rules, Timing, and Reporting

To convert a SEP IRA to a Roth IRA, ask your SEP custodian for a direct trustee-to-trustee transfer into a Roth IRA, then report the full converted amount as ordinary income for the year the transfer happens. The mechanics are simple. The tax consequences are not, because SEP contributions went in pre-tax and every dollar you move now gets stacked on top of your other income for the year.¹ Once inside the Roth, the money grows tax-free, comes out tax-free in retirement, and escapes required minimum distributions during your lifetime. The conversion is permanent; since 2018, recharacterization is no longer allowed.

There is no income limit on doing a conversion. The MAGI caps that restrict annual Roth contributions do not apply here, so high earners can convert freely.² For distribution and conversion purposes, the IRS treats a SEP IRA exactly like a traditional IRA, so no special SEP process exists.

How to Execute the Conversion

Open a Roth IRA if you don’t already have one. You can open it at the same custodian holding your SEP or at a different institution. An existing Roth works fine as the receiving account.

Request a direct trustee-to-trustee transfer. Contact your SEP custodian and ask for a direct conversion to your Roth IRA. The funds move straight from one account to the other without a check being cut to you. No taxes are withheld by default, and the 60-day rollover deadline does not apply.³ The custodian will hand you a conversion election form asking for the receiving Roth account number and the dollar amount.

Decide how much to convert. You can move the whole balance or just part of it. Partial conversions let you control the tax hit year by year. A common approach is to calculate the gap between your current income and the top of your current bracket, then convert just enough to fill that space without spilling into a higher rate.

Save the paperwork. Keep the conversion confirmation. Your custodian will issue a Form 1099-R for the distribution, and you’ll need it at tax time.

Avoid the indirect method, where the custodian mails you a check that you then deposit into a Roth within 60 days. If you miss the window, the whole amount becomes a taxable distribution plus a possible 10% penalty if you’re under 59½. The custodian may also withhold 10% for federal taxes by default, and you’d have to make up that 10% from personal savings to convert the full amount.³

What You’ll Owe in Federal Tax

The full converted amount is added to your ordinary income for the year. Convert $80,000 on top of $120,000 in wages and the IRS treats you as earning $200,000 for bracket purposes. A large single-year conversion can easily push you into the 32% or 35% bracket, which is the main argument for spreading conversions across several tax years. Converting during a low-income year, such as between jobs or in early retirement before Social Security starts, can drop the effective rate significantly.

The Pro-Rata Rule

If your SEP was funded entirely with deductible contributions, the full conversion is taxable and the math ends there. If you have any nondeductible basis in any traditional-type IRA, though, the IRS won’t let you cherry-pick. It aggregates every traditional, SEP, and SIMPLE IRA you own and applies a pro-rata formula.¹

Divide your total nondeductible basis across all traditional-type IRAs by the total year-end value of those same accounts. That fraction is the nontaxable share of any conversion; the rest is ordinary income. If you have $20,000 of nondeductible basis and $200,000 across your traditional and SEP IRAs combined, only 10% of a conversion escapes tax. Convert $50,000, and $45,000 is taxable.

Pay the Tax From Outside Savings

Cover the conversion tax bill from a checking account or other non-retirement money. If you let the custodian withhold taxes from the distribution, the withheld amount is treated as a separate distribution. For anyone under 59½, that piece can trigger the 10% early withdrawal penalty on top of the income tax.⁴ You also end up with less inside the Roth, which defeats the point.

Secondary Costs From the Income Spike

The bracket rate isn’t the whole bill. A large conversion inflates your AGI and MAGI, which can trigger costs that don’t show up in a simple tax calculator.

Medicare IRMAA

If you’re on Medicare or will be within two years, watch this closely. Medicare uses your MAGI from two years back to set Income-Related Monthly Adjustment Amounts on Part B and Part D premiums. For 2026, IRMAA surcharges start at $109,000 for single filers and $218,000 for joint filers, and at the top tier ($500,000+ single, $750,000+ joint) the Part B premium climbs to $689.90 a month versus the standard $202.90.⁵ One large conversion can cost noticeably more in premiums two years out than two smaller ones split across tax years.

Net Investment Income Tax

The 3.8% Net Investment Income Tax applies to the lesser of your net investment income or the amount your MAGI exceeds $200,000 single or $250,000 joint.⁶ The conversion itself isn’t investment income, but the AGI spike can drag your dividends, capital gains, and rental income above the threshold and expose them to the surtax.

Estimated Tax Payments

A large conversion late in the year can trigger an underpayment penalty. To stay safe, your total withholding and estimated payments for the year should equal at least 100% of last year’s tax liability (110% if your AGI was over $150,000), or 90% of the current year’s tax. If you convert in December, one workaround is to raise withholding on wages or pension income. Federal withholding is treated as paid evenly throughout the year regardless of when it was actually taken, which can retroactively cover a late-year conversion.

When to Time It

SEP contributions for a given tax year can be deposited up until the business’s tax filing deadline, including extensions.⁷ Converting before that deadline runs the risk of moving out funds tied to a contribution that hasn’t been finalized. The cleanest window is after all prior-year contributions have settled and before any current-year contribution has landed.

Roth conversions themselves must be completed by December 31 of the year you want the income reported. There is no backdating. A conversion done in January counts for the new tax year, not the one just closed. For anyone spreading a SEP balance across multiple conversion years, December 31 is the hard cutoff for each tranche.

The Five-Year Rule

Money you convert generally can’t come out penalty-free for five years. The clock starts January 1 of the conversion year, and each conversion runs on its own separate five-year period.⁸ Convert $40,000 in 2026 and $30,000 in 2027, and the 2026 batch becomes penalty-free on January 1, 2031, the 2027 batch on January 1, 2032.

The penalty in question is the 10% early withdrawal recapture tax on the taxable portion of the conversion. It only applies if you’re under 59½ and pulling the converted money out inside the five-year window. Once you hit 59½, the early withdrawal penalty no longer applies no matter how recent the conversion.

When Not to Convert

Two situations are dangerous.

SEPP (72(t)) distributions. If you’re taking Substantially Equal Periodic Payments from your SEP to avoid the early withdrawal penalty, do not convert any part of that account. A conversion changes the balance and modifies the payment series, breaking the SEPP. The IRS then applies the 10% early withdrawal penalty retroactively to every distribution you took under the plan, plus interest.⁹ Wait until the SEPP naturally expires (the later of five years or age 59½).

RMD years. Once you’ve reached the RMD age (currently 73), you must take your full required minimum distribution for the year before converting anything else. RMDs cannot themselves be converted or rolled into a Roth.² The RMD obligation is aggregated across your traditional-type IRAs, so satisfy the total from your combined accounts first, then convert what’s left.

Reporting the Conversion

Your SEP custodian will send Form 1099-R by January 31 of the following year. Box 1 shows the gross amount converted, Box 2a the taxable amount (usually the same figure unless you have basis), and Box 7 the distribution code: Code 2 if you’re under 59½, Code 7 if you’re 59½ or older.¹⁰

You must also file Form 8606 with your return for any year you convert.¹¹ Part II is where you report the conversion, apply the pro-rata calculation if you have basis, and land on the final taxable amount. The form is required even when your SEP has zero basis and the whole conversion is taxable. That taxable figure then flows to the IRA distributions line of Form 1040 and is taxed at ordinary rates on top of your other income for the year.

1
Internal Revenue Service. Instructions for Form 8606 (2025)
2
Internal Revenue Service. Publication 590-A (2025), Contributions to Individual Retirement Arrangements (IRAs) – Section: Roth IRAs
3
Internal Revenue Service. Rollovers of Retirement Plan and IRA Distributions
4
Internal Revenue Service. Topic No. 557, Additional Tax on Early Distributions From Traditional and Roth IRAs
5
Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles
6
Internal Revenue Service. Topic No. 559, Net Investment Income Tax
7
Internal Revenue Service. Retirement Plans FAQs Regarding SEPs
8
Internal Revenue Service. Publication 590-B (2025), Distributions From Individual Retirement Arrangements (IRAs) – Section: Conversions
9
Internal Revenue Service. Substantially Equal Periodic Payments
10
Internal Revenue Service. 2025 Instructions for Forms 1099-R and 5498
11
Internal Revenue Service. About Form 8606, Nondeductible IRAs