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M04 · Module 4 of 11

Advanced contribution strategies

Once your income climbs past a certain point, the front door to a Roth IRA closes, and the simple “just contribute” advice stops applying. This module covers the legal workarounds high earners use to keep funding Roth accounts anyway, plus the conversion timing that turns a low-income year into a tax-saving opportunity.

What you’ll take away

  • Why a high income blocks you from contributing to a Roth IRA directly
  • How a backdoor Roth contribution restores Roth access through a two-step move
  • How the pro-rata rule can quietly tax a backdoor conversion, and how to clear it first
  • When a mega backdoor Roth is possible and how much it can add
  • How converting pre-tax balances in low-income years fills a bracket without overshooting

Why your income locks you out of direct Roth contributions

A Roth IRA lets you contribute after-tax dollars, grow them tax-free, and withdraw them tax-free in retirement. That deal is too good for the tax code to leave open to everyone, so Congress capped who can use it directly. Above a modified adjusted gross income (MAGI) threshold that depends on your filing status, your allowed direct Roth contribution phases down, then hits zero. The phaseout begins at $242,000 (2026), $236,000 (2025) for married couples filing jointly and at $153,000 (2026), $150,000 (2025) for single filers, and the contribution disappears entirely above the top of that range.

For most readers of this module, that means a direct Roth IRA contribution is simply off the table. MAGI here is your adjusted gross income with a few deductions added back, and a strong W-2 or business income usually clears the ceiling on its own.

Two points keep people from giving up too early. First, the income limit applies to the Roth IRA, the individual account. It does not touch a Roth 401(k) offered through your employer, which has no income limit at all; if your plan offers a Roth deferral option, you can use it regardless of income. Second, the limit blocks the direct contribution path, and a separate, fully legal path exists. That path is the backdoor Roth.

The accounts and rules underneath all of this (how a Roth differs from a traditional account, how deductibility works) are covered in the Roth and traditional account basics these strategies build on. This module assumes you already have that grounding and focuses on what high earners do once the direct route is closed.

How the backdoor Roth gets you in anyway

A backdoor Roth is a two-step sequence that lands money in a Roth IRA without a direct contribution. It works because two separate rules don’t talk to each other: the income limit applies to Roth contributions, but there is no income limit on converting a traditional IRA to a Roth IRA. You use the open door to reach the closed one.

The steps are:

  1. Contribute to a traditional IRA, nondeductible. Anyone with earned income can put money into a traditional IRA up to $7,500 (2026), $7,000 (2025). At your income, you cannot deduct that contribution, so it becomes after-tax basis in the account. That is fine, and expected.
  2. Convert that traditional IRA to a Roth IRA. Shortly after, you convert the balance to a Roth. Because you already paid tax on the money (it was nondeductible), the conversion of that contribution is not taxed again. Any small gains earned between the two steps are taxable, which is why people often convert quickly.

The result is money sitting in a Roth IRA, growing tax-free, that you were not allowed to put there directly. Nothing about this is a loophole in the pejorative sense; the IRS has acknowledged the strategy, and it appears on millions of returns. You report the nondeductible contribution on Form 8606, which tracks your after-tax basis so you are not taxed twice.

One detail trips up filers every year: the nondeductible contribution must be reported on Form 8606 even though it produced no deduction. Skipping that form is how people lose track of basis and end up paying tax twice on the same dollars.

If the backdoor were always this clean, this module would be short. It is not, because of one rule that can turn a “tax-free” conversion into a partly taxable one.

How the pro-rata rule trips people up, and how to clear it

This is the highest-stakes lesson in the module. Get it wrong and a move you expected to be tax-free generates a surprise tax bill, sometimes a large one.

The trap starts with a fact most people don’t know: when you convert any traditional IRA money to Roth, the IRS does not let you cherry-pick which dollars you are converting. It treats all of your traditional, SEP, and SIMPLE IRAs as one combined pot and applies a single ratio. This is the pro-rata rule. The taxable share of any conversion equals the pre-tax portion of that combined pot.

Walk through what that means. Suppose you have an old rollover IRA holding $200,000 of pre-tax money (a previous 401(k) you rolled out, never taxed). Now you make a fresh nondeductible contribution of $7,500 (2026), $7,000 (2025) and try to convert just that contribution to Roth, expecting no tax. The IRS does not see a clean nondeductible dollar. It sees a combined IRA balance that is mostly pre-tax, with only a small slice of after-tax basis. Your conversion is taxed in that same proportion. If the after-tax basis is a small fraction of the combined balance, then most of what you convert is treated as pre-tax and taxed as ordinary income, even though you intended to convert only the after-tax contribution you just made.

Two consequences follow, and both are bad. You owe ordinary-income tax on the pre-tax portion of the conversion, which can be thousands of dollars you did not plan for. And the after-tax basis you did not convert stays stranded in the IRA, spread pro-rata across the pot, complicating every future conversion. The pre-tax balance does not have to be huge to cause this; any meaningful pre-tax IRA balance pollutes every backdoor conversion you attempt while it sits there.

There is a clean way out, and it is the reason this lesson matters so much: move the pre-tax IRA money where the pro-rata rule cannot see it. The combined-pot calculation looks only at IRAs. It ignores employer plans. So if your 401(k) accepts incoming rollovers (most do), you can roll your pre-tax traditional, SEP, and SIMPLE IRA balances into the 401(k) before year-end. Once that pre-tax money is inside the 401(k), your IRA balance is either zero or pure after-tax basis, and a backdoor conversion converts cleanly with no pro-rata tax.

Timing matters in a specific way. The pro-rata calculation uses your combined pre-tax IRA balance as of December 31 of the conversion year, not the day you convert. Clearing the IRA in November after converting in March does not undo the tax; the balance has to be gone by year-end. Order the steps so the rollover into the 401(k) completes before December 31 of the year you convert.

Because the arithmetic is unforgiving and the inputs are specific to you, work your exact numbers through backdoor Roth pro-rata calculator before you convert. It takes your combined pre-tax IRA balances and your planned conversion and shows the taxable portion, so you can see whether you need to clear an IRA first. What you do with that result (whether and when to roll the IRA into your plan) is a personal decision, and a CFP is where that conversation belongs.

Mega backdoor Roth, when your plan allows it

A regular backdoor Roth moves a few thousand dollars a year into a Roth IRA. A mega backdoor Roth can move many times that, through your 401(k), but it works only if your specific employer plan is built for it. Whether yours qualifies is the entire question, so start there.

Three numbers define a 401(k). Your own pre-tax or Roth salary deferral is capped at $24,500 (2026), $23,500 (2025). Your employer’s match sits on top of that. And there is a much higher ceiling on total contributions from all sources combined, the total addition limit of $72,000 (2026), $70,000 (2025). The gap between what you plus your employer actually contribute and that total addition limit is unused space. A mega backdoor Roth fills that gap with after-tax dollars and then converts them to Roth.

It depends on two plan features, and both have to be present:

  1. The plan must allow employee after-tax contributions. These are a third contribution type, separate from pre-tax and Roth deferrals. Many plans do not offer them at all.
  2. The plan must allow you to get that after-tax money into Roth, either through an in-plan Roth conversion or through in-service withdrawals you roll to a Roth IRA. Without a conversion path, after-tax contributions just sit there growing in a tax-inefficient way, which defeats the purpose.

When both features exist, the sequence is: max your regular deferral, contribute after-tax dollars into the remaining space under the total addition limit, and convert those after-tax dollars to Roth promptly so little or no gain accrues in the after-tax bucket. Done right, you add Roth money far beyond what an IRA allows, every year.

The conversion-speed point matters for the same reason it did in the plain backdoor: any gains that accrue in the after-tax sub-account before you convert are taxable on conversion. Frequent or automatic in-plan conversions keep that taxable gain near zero.

This lesson is gated on plan availability for a reason. If your plan lacks after-tax contributions or a conversion path, the mega backdoor is not available to you this year, and no workaround changes that; the feature has to exist in the plan document. To see how much room you actually have, mega backdoor Roth capacity calculator takes your deferrals and employer contributions and computes the after-tax space left under the total addition limit.

Filling brackets with Roth conversions

The strategies above are about getting new money into Roth. Conversions are also a tool for the pre-tax balances you already hold. Converting pre-tax 401(k) or IRA money to Roth means paying ordinary-income tax on the converted amount now, in exchange for tax-free growth and withdrawals later. Whether that trade pays off comes down to a single comparison: your tax rate now versus your expected tax rate when you would otherwise withdraw the money.

That comparison is why low-income years are the opening. A gap year between jobs, an early-retirement window before required distributions and Social Security begin, a year a business runs at a loss: in any of these, your marginal rate can drop well below where it sits in a peak-earning year. Converting pre-tax dollars during that dip means paying tax at the low rate instead of the high one, and the converted balance then grows tax-free for good.

The technique is bracket-filling. Each conversion dollar stacks on top of your other taxable income and is taxed at your marginal rate. The aim is to convert just enough to reach the top of a chosen tax bracket without spilling a single dollar into the next, higher bracket. Convert too little and you waste cheap room you will never get back at that rate. Convert too much and the overflow is taxed at a higher rate than the strategy assumes, which can erase the benefit.

Brackets are not the only ceiling to respect, and this is where high earners get caught. The same dollars that fill a bracket also raise your MAGI, which feeds several thresholds and phaseouts: the net investment income tax, the income-related surcharge on Medicare premiums (IRMAA) for those near or in retirement, and various credit and deduction phaseouts. A conversion sized perfectly to a bracket edge can still be a mistake if it pushes you across one of those cliffs. The full set of brackets, thresholds, and phaseouts a conversion has to fit under is the subject of the brackets and phaseouts a conversion has to fit under; size a conversion against all of them, not the income-tax brackets alone.

One more constraint deserves a flag. Pay the conversion tax from outside the retirement account, ideally from taxable savings. Using part of the converted balance to cover the tax shrinks the amount that reaches the Roth and, before a certain age, can trigger an early-withdrawal penalty on the portion withheld. The conversion works best when every converted dollar lands in the Roth and the tax is paid separately.

Sizing a conversion to a bracket edge while staying under every relevant threshold is exactly the kind of arithmetic worth running before you act. Roth conversion / bracket-filling planner takes your projected income for the year and shows how much you can convert before crossing a bracket or a phaseout. It shows you the room; deciding how much to actually convert is a personal call, and a CFP is where that decision gets made.

Putting it together

High income closes the direct Roth door, and these strategies are how earners keep funding Roth accounts anyway. A backdoor Roth restores IRA access through a nondeductible contribution and a conversion, as long as you clear any pre-tax IRA balance first so the pro-rata rule cannot tax the move. A mega backdoor Roth adds far more, but only when your plan offers after-tax contributions plus a conversion path. And Roth conversions let you reprice pre-tax balances in low-income years, filling a bracket without overshooting it or tripping a phaseout. Each one rewards getting the sequence and the timing right, which is why each has a calculator attached.

Connections

This module explains how these strategies work. For what to do in your own situation, the platform hands off to a CFP.