Getting started · 2025 and 2026
What Is a Backdoor Roth IRA? Complete 2025 & 2026 Step-by-Step Guide
Published by Moss Ladder · Updated October 17, 2026 · Editorial policy
Executive summary
A backdoor Roth IRA uses two separately reportable transactions: an eligible traditional IRA contribution that is not deducted, followed by a Roth conversion. It can help a high-income saver fund a Roth IRA, but existing IRA balances, compensation, contribution limits and reporting history determine the result. Start with the complete account inventory rather than a new account application.
Educational guidance for ordinary scenarios. Check the official form's year and filing branches and obtain advice for your actual records.
Try the related planning tool1. Check which contribution route is available
A direct Roth IRA contribution is governed by modified adjusted gross income, filing status and the annual regular IRA contribution limit. For 2025, the Roth phase-out is $150,000–$165,000 for single and head-of-household filers and $236,000–$246,000 for joint filers. For 2026, those ranges are $153,000–$168,000 and $242,000–$252,000. A married separate filer who lived with a spouse during the year generally uses the $0–$10,000 range. Living apart all year can change the applicable category. Use the IRS MAGI worksheet, rather than assuming salary equals MAGI.
The regular contribution limit is shared between traditional and Roth IRAs: $7,000 for 2025, or $8,000 at age 50 or older; $7,500 for 2026, or $8,600 at age 50 or older. Eligible compensation can reduce the available amount further. A conversion does not consume that limit, but making a nondeductible contribution still does. An employer SEP contribution or a 401(k) elective deferral follows different rules. A high income does not remove the compensation requirement or permit a second full regular contribution at another custodian.
2. Designate the contribution and its deduction treatment
A traditional IRA contribution may be deductible, partially deductible or nondeductible. Workplace-plan coverage and the applicable deduction MAGI rules determine whether a deduction is available; choosing the backdoor workflow does not establish deduction eligibility. If a contribution is not deducted, Form 8606 records the resulting basis. Keep the custodian confirmation identifying the contribution year and reconcile any deduction actually taken on the return. The statement's contribution amount and the return's nondeductible amount are not automatically the same number.
Contributions for a tax year can generally be made through the ordinary filing due date in the following year, excluding extensions, subject to the applicable IRS rules and any announced relief. A contribution made in March 2026 and designated for 2025 belongs in the 2025 contribution records. A custodian may default a deposit to the current year unless you specify otherwise. Correct an incorrect designation through the custodian's process before relying on the tax treatment. Do not create a second basis entry merely because the deposit and conversion appear on statements from different calendar years.
3. Convert only after understanding the account inventory
The conversion is a distribution from a traditional IRA into a Roth IRA, typically arranged through the custodian. Cash must be available under that custodian's settlement and operational rules; there is no universal number of waiting days that makes the transaction tax free. Market gains between contribution and conversion can be taxable. Ask about unsettled trades, residual interest and processing cutoffs rather than assuming that submitting an online request completes the conversion that day. Keep the confirmation of the actual completion date and amount.
IRC § 408(d)(2) generally aggregates your owned traditional, traditional SEP and traditional SIMPLE IRAs for allocation of basis. A new empty IRA at a different brokerage does not isolate a nondeductible contribution from an existing rollover IRA. Your spouse's separately owned IRA is not added to yours, even on a joint return. Employer qualified-plan assets are generally outside the IRA year-end balance, but a later rollover from a plan into an IRA can bring those assets into the calculation. Inherited and special transactions need their own analysis.
Keep the two steps in separate records
Record the contribution tax year, deposit date, settlement confirmation and conversion completion date separately. A bank transfer request is not proof that the conversion completed. Compare the confirmation with the final custodian forms, including residual interest, before preparing the return. This small recordkeeping step makes a later year-end reconciliation much easier.
Clean 2026 contribution and conversion
This invented example assumes one taxpayer, documented basis, eligible ordinary transactions, no special repayment and no tax withholding. Dollar amounts are planning values. Use the official form's filing branches; a displayed line is not automatically a required entry on a filed return. The 2026 examples apply published 2026 contribution limits with the 2025 allocation structure.
| Form 8606 line | Modeled amount |
|---|---|
| 1 | $7,500.00 |
| 2 | $0.00 |
| 3 | $7,500.00 |
| 4 | $0.00 |
| 5 | $7,500.00 |
| 6 | $0.00 |
| 7 | $0.00 |
| 8 | $7,500.00 |
| 9 | $7,500.00 |
| 10 | 1.000 |
| 11 | $7,500.00 |
| 12 | $0.00 |
| 13 | $7,500.00 |
| 14 | $0.00 |
| 16 | $7,500.00 |
| 17 | $7,500.00 |
| 18 | $0.00 |
| 15a | $0.00 |
| 15b | $0.00 |
| 15c | $0.00 |
4. Compare a clean conversion with a mixed-balance conversion
In the clean example, assume a timely $7,500 nondeductible 2026 contribution, a $7,500 conversion, no other distributions and no traditional, SEP or SIMPLE IRA value at year end. The available basis and conversion pool are both $7,500, so all of the conversion is tax free. This result depends on the stated facts; the word backdoor does not create an exemption. If the account earns $45 before conversion and $7,545 is converted, $45 is taxable under the ordinary model, with all $7,500 basis recovered.
Now assume $7,000 available basis, a $7,000 conversion and $21,000 left in applicable IRAs at December 31. The pool is $28,000 and the tax-free ratio is 25%. Only $1,750 of the conversion is tax free; $5,250 is taxable and $5,250 basis remains. The remaining basis is a record for later distributions, not a deduction taken immediately. Test these assumptions in the pro-rata calculator and compare the taxable income separately from the estimated federal tax. Tax withheld from the transaction is another distribution issue, not a discount on the conversion amount.
5. Finish the reporting and review the wider decision
The distributing custodian generally issues Form 1099-R for the conversion year. Form 5498 provides contribution-related information, but may arrive after the ordinary filing deadline and does not reconstruct your lifetime basis. Your tax return uses the appropriate Form 8606 Parts I and II, with the correct filing branches. Married joint filers prepare separate Forms 8606 when both spouses are required to file. Review Form 1040 IRA distribution reporting and reconcile taxable amounts instead of accepting a custodian's unknown-taxability designation as a final answer.
Before repeating the workflow, check whether an incoming rollover, a SIMPLE restriction, an excess contribution or missing historical basis changes the facts. Roth conversions cannot generally be undone through recharacterization. State taxes, income-related benefits, future withdrawal rules and the money used to pay tax also matter. Retain statements, contribution and conversion confirmations, Forms 8606 and the return workpapers. The checklist tool helps organize these steps; the methodology explains the model's boundaries. A complete checklist is preparation evidence, not a determination that an individual transaction is suitable.
About the publisher: Moss Ladder
Moss Ladder owns and publishes RothProRata.com, an independent educational website about IRA basis, Roth conversions and Form 8606. The guides connect official sources with invented examples, document checklists and browser-local planning tools.
AI-assisted tools help prepare explanations and software. Numerical allocation examples state their assumptions and are checked with automated calculations. These engineering checks do not constitute independent CPA or Enrolled Agent review, and no professional tax credential is claimed.
Official sources
Source year and transaction type matter. Citations support the explanation; they do not imply government endorsement.
- U.S. Code (2024 edition): IRC § 408(d)(2) aggregation and § 408(d)(3) rollovers
- IRS: 2025 Form 8606, Parts I and II
- IRS: 2025 Form 8606 instructions (basis, year-end values and conversions)
- IRS: Publication 590-A (2025), contributions and rollovers
- IRS: Publication 590-B (2025), distributions and Roth five-year rules