Backdoor Roth and Mega Backdoor Roth With an Illiquid IRA (2026)

The 2026 numbers, from the notice

Every 2026 dollar figure in this guide comes from IRS Notice 2025-67 (“2026 Amounts Relating to Retirement Plans and IRAs, as Adjusted for Changes in Cost-of-Living”) or from Publication 590-A's “What's New for 2026”, which repeats the IRA figures.

Source: IRS Notice 2025-67 and Publication 590-A (2025), read and saved October 20, 2026.

Two points about the Roth phase-out. First, the ranges are $10,000 wide for joint filers and $15,000 wide for single filers, because section 408A(c)(3)(A) divides by “$15,000 ($10,000 in the case of a joint return or a married individual filing a separate return)”. Halfway through the range a joint filer at $247,000 can contribute $3,750 and a single filer at $160,500 can contribute $3,750 (our arithmetic; the rounding rules of section 219(g)(2) can move the last dollars). Second, the modified AGI that decides it leaves out the conversion: section 408A(c)(3)(B)(i) takes AGI “except that any amount included in gross income under subsection (d)(3) shall not be taken into account”. A backdoor conversion therefore does not push you further over the limit (our reading), though 26 CFR 1.408A-4 A-9 says the taxable conversion amount does count for the taxable part of Social Security and for the passive-loss allowance. For the Medicare side, see our IRMAA brackets guide.

How a backdoor Roth works, and what the $0 conversion tax rests on

The backdoor is two steps the Code allows separately.

1. A nondeductible contribution to a traditional IRA. Section 408(o)(2)(B)(i) sets the nondeductible limit as the amount allowable as a deduction without the income phase-out of section 219(g), minus the amount allowable with it. For someone covered by a workplace plan and above the deduction phase-out ranges in the table, the deduction is zero and the whole $7,500 is nondeductible. Below them, section 408(o)(2)(B)(ii) lets a taxpayer elect not to deduct, which raises the nondeductible limit. The designation is made on the return, per section 408(o)(2)(C)(ii), which in practice means Form 8606.
2. A conversion to a Roth IRA. Section 408A(d)(3)(C) says “The conversion of an individual retirement plan (other than a Roth IRA) to a Roth IRA shall be treated for purposes of this paragraph as a distribution to which this paragraph applies”, and (d)(3)(A)(i) puts in gross income “any amount which would be includible were it not part of a qualified rollover contribution”. There is no income test on the conversion: Pub. L. 109-222 section 512(a)(1) struck out the former subparagraph (B) of section 408A(c)(3), which had barred conversions above a set AGI.

The conversion is taxed under the ordinary IRA rule, and that is where the $0 comes from. Section 408(d)(1) taxes IRA distributions “in the manner provided under section 72”, and 26 CFR 1.408A-4 A-7(a) says “any portion of the distribution or transfer that is treated as a return of basis under section 408(d)(1) and (2) is not includible in gross income as a result of the conversion”. After-tax dollars are basis, and basis comes out tax-free. If you convert exactly what you contributed and you have no other pre-tax IRA money on December 31, Form 8606 line 10 is 1.000000, line 11 equals line 8 and line 18 is zero (our arithmetic). Growth between the contribution and the conversion is not basis: contributing $7,500 and converting $7,520 leaves $20 taxable (our arithmetic).

Neither the Code sections above nor the Form 8606 instructions set a waiting period between the two steps (our reading of the texts we read). Whether to wait is a risk question, covered under the step transaction doctrine below.

Form 8606 line by line

Part I of Form 8606 is where the pro-rata fraction lives. The lines below are the 2025 form, the latest on IRS.gov on October 20, 2026; the 2026 form, filed in 2027, uses the same structure with December 31, 2026 in line 6 (our reading). File one for each spouse.

Source: Form 8606 (2025) and Instructions for Form 8606 (2025), saved October 20, 2026.

Three details from the instructions matter for this reader. “Traditional IRA” includes “traditional SEP IRAs and traditional SIMPLE IRAs”. Employer contributions to a SEP or SIMPLE IRA are not nondeductible contributions. And line 6 includes an “outstanding rollover”, which for line 6 means a distribution received after November 1 that was rolled over into another traditional IRA in the following year within the 60-day period; a rollover to an employer plan is not described that way (our reading). The instructions also say “A statement should be sent to you by January 31, 2026, showing the value of each IRA on December 31, 2025”; for 2026 the Form 5498 instructions put the participant statement at February 1, 2027.

Worked example: one $7,500 backdoor next to an illiquid IRA

All figures below are our arithmetic on assumed numbers, run by a script; every row is also in the data download. The assumed investor makes a $7,500 nondeductible contribution (Form 8606 line 1), has no earlier basis (line 2 is $0), takes no other distributions (line 7 is $0) and converts exactly $7,500 (line 8). The only thing that changes between rows is the December 31 value of the other traditional, SEP and SIMPLE IRAs (line 6). The tax column assumes a 35% federal marginal rate on the taxable amount, an assumption of ours, not a figure from any IRS document.

Our arithmetic. Line 10 is carried to six places for clarity; the form asks for at least three.

The pattern is that the pro-rata rule does not scale gently. With even $50,000 in another IRA, 87% of the conversion is taxable; with $400,000 it is 98.2%. A backdoor Roth next to a large illiquid IRA is, in practice, a taxable conversion of $7,500 that also leaves $7,362 of basis stuck in the traditional IRA (line 14), to be recovered slowly. The existing guide to Roth conversions with illiquid IRA assets covers the other side: converting the illiquid IRA itself and paying the tax from outside the account.

Does the valuation change the answer?

It depends on how much basis you carry. For one year of contributions the illiquid IRA's value hardly matters, because the fraction is small whatever the denominator is.

Our arithmetic. The first group assumes line 1 is $7,500 and line 8 is $7,500; the second assumes line 2 is $100,000, nothing new is contributed and line 8 is $50,000.

In the first group, tripling the value from $200,000 to $600,000 moves the tax by $62. In the second group, the same change moves it by $4,308. Where basis has built up over several years of backdoors that were taxed in part, or after a rollover of after-tax money into an IRA, the December 31 number on the custodian's statement is worth real money. That is the reason to ask the custodian how it values each illiquid asset, from which appraisal or sponsor estimate, and as of which date (see the valuation section below).

Basis carries forward, and a mark-down helps only a little

Form 8606 line 14 becomes next year's line 2, so the basis that the first year could not use is still there.

After two years the investor has $14,559 of unrecovered basis and has paid ordinary income tax on $14,559 of what was meant to be tax-free (our arithmetic). The basis is not lost: it is recovered when the traditional IRAs are eventually distributed or converted, as Form 8606 line 14 tracks it. The cost is timing and the 35% rate in our assumption.

Why illiquid assets matter: the December 31 value

Section 408(d)(2)(C) says “the value of the contract, income on the contract, and investment in the contract shall be computed as of the close of the calendar year in which the taxable year begins”. For an IRA that holds a non-traded REIT, an LLC interest, a private note or real estate, the Code does not say how to get that number, and the reporting rules put the burden on the custodian.

• Form 5498 box 5. The instructions for Forms 1099-R and 5498 (2026) say the box is “the FMV of the account on December 31, 2026” and that “Trustees and custodians are responsible for ensuring that all IRA assets (including those not traded on established markets or not having a readily determinable market value) are valued annually at their FMV.”
• Boxes 15a and 15b. Assets “not readily tradable on an established securities market or option exchange, or that do not have a readily available FMV, must be reported at the FMV determined as of December 31, 2026”. Box 15b codes include C for an interest in an LLC or similar entity, D for real estate and E for an interest in a partnership or trust.
• The participant statement. It “must show the value of the participant's account as of December 31, 2026” and is due by February 1, 2027; Form 5498 goes to the IRS by May 31, 2027.
• A distribution in kind. If the IRA distributes the asset itself, the Form 1099-R instructions say to include in box 1 “the FMV of the securities or other property on the date of distribution”, and a traditional IRA distribution of assets without a readily available FMV gets code K.

The practical point is that the number on your Form 8606 line 6 should match the box 5 value on the custodian's Form 5498 for the same December 31, and that both come from a valuation you can ask for in writing. Our guide to self-directed IRA real estate rules covers how the custodian ends up holding the asset, and the RMD guide for illiquid IRA assets shows what the same year-end value does to the required distribution.

The reverse rollover fix, and why it stalls with an illiquid IRA

The standard fix for the pro-rata rule is to move the pre-tax IRA money into an employer plan before December 31, so that line 6 is small. The Code allows it. Section 408(d)(3)(A)(ii) lets an amount distributed from an IRA go “into an eligible retirement plan for the benefit of such individual not later than the 60th day”, “except that the maximum amount which may be paid into such plan may not exceed the portion of the amount received which is includible in gross income”. Section 408(d)(3)(H) adds a rule that makes it work when you have basis: the rolled-over portion “shall be treated as from income on the contract (to the extent of the aggregate income on the contract from all individual retirement plans of the distributee)”. In Publication 590-A's words, the effect is “to make the amount in your traditional IRAs that you can roll over to an eligible retirement plan as large as possible”.

Three limits apply, and the third is the one that matters here.

1. The plan decides. Publication 590-A: “Qualified plans may, but aren’t required to, accept such rollovers.” An employer 401(k), a 403(b) or a Solo 401(k) you set up for your own business each has a plan document that either accepts incoming IRA money or does not.
2. Only the includible part moves. The pre-tax amount is rolled; your after-tax basis stays in the IRA.
3. The property has to go with it. The statute speaks of “the entire amount received (including money and any other property)”, and for a rollover into a Roth IRA, Publication 590-A says “You must roll over into the Roth IRA the same property you received from the traditional IRA.” An IRA owner who holds non-traded REIT shares, an LLC interest or deeded real estate can roll the asset into a plan only if the plan, its trustee and its recordkeeper will hold that property. The Code does not require them to (our reading); our guide to the DOL rule on 401(k) alternative investments covers what a plan can hold at all, and the Solo 401(k) versus SDIRA comparison covers the plan a self-employed investor can build for the purpose.

The effect on the numbers is easy to see. Take the $420,000 IRA of the earlier table, $400,000 illiquid and $20,000 cash (our arithmetic).

The cash-only rollover changes the taxable amount by $6. The fix works completely only when the illiquid asset can move, and the last row shows the other way to empty line 6: convert everything, which turns the pro-rata problem into a $400,000 tax bill at our assumed rate. Nothing in the sources makes either route easier; both depend on the asset. If neither is available, the realistic choices are to skip the IRA backdoor and use a route that does not touch line 6 (a Roth contribution directly if your income allows it, a Roth deferral or a mega backdoor inside a plan), or to accept the taxable conversion and track the basis on Form 8606.

The mega backdoor Roth

The mega backdoor Roth is an employer-plan strategy, not an IRA strategy. It has three parts, and each must be allowed by the plan document: after-tax employee contributions, and then either an in-plan Roth rollover or an in-service distribution to a Roth IRA.

The limit. Section 415(c)(1) caps annual additions at the lesser of a dollar amount and 100 percent of compensation; Notice 2025-67 sets the dollar amount for 2026 at $72,000. Annual additions are employer contributions, employee contributions and forfeitures (section 415(c)(2); 26 CFR 1.415(c)-1(b)(1)), and the regulation says the term for employee contributions (paragraph (b)(3)) “includes mandatory employee contributions … as well as voluntary employee contributions”. A catch-up contribution under section 414(v) “does not give rise to an annual addition” (26 CFR 1.415(c)-1(b)(2)(ii)(B)). Elective deferrals are made through the employer, so we count them with employer contributions (our reading).

After-tax contributions. The regulation under section 401(m) defines employee contributions as contributions “designated or treated at the time of contribution as after-tax employee contributions” and allocated to an individual account. Section 401(m)(1) subjects them to a contribution percentage test, so a plan's testing can limit what a highly compensated employee (the 2026 threshold is $160,000) may put in.

Getting the money into a Roth. Two routes exist, and both involve the plan's terms.

• In-plan Roth rollover. Section 402A(c)(4)(A) includes in gross income “any amount which would be includible were it not part of a qualified rollover contribution”, so only the earnings on the after-tax money are taxed if you convert promptly. With $37,500 of after-tax contributions and $1,500 of earnings, converting $39,000 leaves $1,500 taxable (our arithmetic). Notice 2013-74 Q&A-6 lets a plan “limit the type of contributions eligible for an in-plan Roth rollover and the frequency of in-plan Roth rollovers”, which is why some plans allow it only once a quarter or once a year, and Q&A-4 warns that a participant making an in-plan Roth rollover “may need to increase his or her withholding or make estimated tax payments”.
• In-service distribution to a Roth IRA. Notice 2014-54, which the Form 1099-R instructions cite for “allocation of after-tax amounts to rollovers”, governs how pre-tax and after-tax amounts are split when a plan pays several destinations at once. It begins from the rule that each distribution carries a pro-rata share: “each distribution from the account (other than a distribution that is paid as part of an annuity, which is subject to a different rule) will include a pro rata share of both after-tax and pretax amounts”. Its Example 4 then shows that on a $100,000 distribution from a $250,000 account ($200,000 pretax, $50,000 after-tax), the participant “is permitted to allocate the $80,000 that consists entirely of pretax amounts to the traditional IRA so that the $20,000 rolled over to the Roth IRA consists entirely of after-tax amounts”. On our own assumed account of $237,500 ($200,000 pretax and $37,500 after-tax), a $37,500 distribution carries $31,579 of pretax and $5,921 of after-tax amounts (our arithmetic). To put only after-tax money into a Roth IRA, the pretax part has to go somewhere else.

Notice 2014-54 does not use the words mega backdoor Roth, and we found nothing in the documents we read that does; it is the allocation notice that people cite for the technique. Whether your plan converts the after-tax source alone or applies the whole-account share is a plan-administrator question (not verified; plan-specific).

How it meets the IRA problem. Section 408(d)(2) aggregates “all individual retirement plans”; it does not reach a 401(k) account. A mega backdoor conversion inside the plan therefore does not enter Form 8606 line 6, and an illiquid IRA elsewhere does not change its tax (our reading). The one place the two meet is the pretax slice: if Notice 2014-54 allocation sends it to a traditional IRA, that traditional IRA is on line 6 on December 31.

The step transaction doctrine: where it stands

The step transaction doctrine is a judicial doctrine that can collapse a series of formally separate steps into one. We saved no case law for this page, so the status below is limited to what Congress, the Code and the IRS forms say.

We found no IRS ruling, regulation or court decision in the documents we read that applies the step transaction doctrine to a nondeductible contribution followed by a conversion. That is an absence in our reading list, not a guarantee. If the doctrine were applied, the contribution would be tested against the Roth income limit, and Publication 590-A says an excess contribution “is subject to a 6% excise tax” unless withdrawn in time. Whether to leave a gap between the contribution and the conversion is a judgment for your CPA; the texts we read set none.

The 5-year rules

Three separate clocks run, and the backdoor starts at least one of them.

Sources: 26 U.S.C. 408A(d)(2)(B); 26 CFR 1.408A-6; Publication 590-B (2025); Notice 2013-74.

The part of a conversion that was included in income is exposed to the 10% additional tax if you withdraw it within its own 5 years, before age 59 1/2, and no exception applies; the basis part is not. Section 408A(d)(3)(A)(ii) switches off the 10% tax on the conversion itself.

Before December 31, 2026: what to settle

• Is there any pre-tax IRA money? Add up traditional, SEP and SIMPLE IRAs, with the illiquid assets at the custodian's value. If the total is near zero, the plain backdoor is clean.
• If not, can the pre-tax money go into a plan? Ask the plan administrator in writing whether the plan accepts rollovers from IRAs, in cash and in kind, and by what date a direct rollover must be complete to be out of the December 31 value.
• Can the illiquid asset be valued? Ask the custodian for the value it will report for December 31, 2026, the source and the date. Compare it with the Form 5498 box 15a entry it filed last year.
• Does your income need the backdoor at all? At or above $252,000 (joint) or $168,000 (single) of modified AGI a direct Roth contribution is closed; below the start of the range it is open.
• Is a mega backdoor in your plan? Ask for the plan's after-tax contribution provision, the in-plan conversion or in-service distribution provision, how often you can convert and what testing limits apply to highly compensated employees.
• Do you want to convert the illiquid IRA itself? That is a different decision with its own tax bill; see our Roth conversion guide for illiquid IRA assets.
• Keep the paper. Form 8606 each year, the Form 5498 box 5 and 15a values, the Form 1099-R for the conversion and any plan notices.

What a reader can do with this

• Run your own line 6. List every traditional, SEP and SIMPLE IRA and the value each custodian reported on its last Form 5498 (box 5, and box 15a for the illiquid asset). Put the total in the table above to see your fraction.
• Test the valuation in two directions. Recompute the fraction with the illiquid IRA at today's value and at 30% lower or higher. If the taxable amount barely moves, as in the first column of the sensitivity table, the valuation is not your problem; if it moves a lot, ask for the appraisal date.
• Ask the plan first, then act. A reverse rollover cannot be undone once the IRA money is in a plan that will not let it out, so get the plan's rollover provisions in writing before moving anything.
• Separate the three tools. The IRA backdoor depends on line 6; the mega backdoor depends on the plan document; a direct Roth contribution depends on modified AGI. A reader can use whichever the facts allow.
• See the self-employed alternative. If you have self-employment income, Solo 401(k) versus Roth IRA for real estate crowdfunding compares the plan route with the IRA route.

FAQ

Sources, read and saved on October 20, 2026: 26 U.S.C. 219, 401, 402, 402A, 408, 408A, 414 and 415 (Cornell Legal Information Institute); 26 CFR 1.401(m)-1, 1.402A-1, 1.408-4, 1.408A-4, 1.408A-6 and 1.415(c)-1 (eCFR, current to October 6, 2026); IRS Notice 2025-67, Notice 2014-54 and Notice 2013-74; Form 8606 and Instructions for Form 8606 (2025); Instructions for Forms 1099-R and 5498 (2026); Publications 590-A and 590-B (2025); House Report 115-466 (conference report on H.R. 1, December 15, 2017); and H.R. 5376, 117th Congress (engrossed in House). The investor, the balances, the 35% tax rate, the 2027 limit and the 10% mark-down are assumptions; all sums are our arithmetic. This is analysis of public documents, not investment, legal or tax advice.