Over the Roth Income Limit? The Backdoor (and Mega Backdoor) Explained

A small and a large open navy door with mint light, rising gold coin stacks, and sprouts spilling out — the backdoor and mega backdoor Roth paths to tax-free growth

At the end of Part 1: The Investing Order of Operations, I left two doors cracked open: the backdoor Roth and the mega backdoor Roth. If you read “income limits apply” on the Roth IRA step and felt locked out — this post is for you.

Because here’s the thing: the IRS didn’t lock the door. It just moved it.

First, a 60-Second Refresher on Why Roth Money Is Worth Chasing

Roth dollars are taxed once — now — and then never again. No tax on decades of growth. No tax on qualified withdrawals in retirement. No required minimum distributions forcing money out of a Roth IRA on the IRS’s schedule. That’s why high earners go through extra paperwork to get money into Roth accounts.

The catch: direct Roth IRA contributions phase out by income. For 2026:

Filing status Full contribution below Phased out completely at
Single / Head of household $153,000 MAGI $168,000
Married filing jointly $242,000 MAGI $252,000

Over those numbers? You can’t contribute directly. But “directly” is doing a lot of work in that sentence.

The Backdoor Roth IRA: Three Steps and a Form

There’s no income limit on contributing to a traditional IRA. And there’s no income limit on converting a traditional IRA to a Roth. Put those two facts together and you get the backdoor Roth:

1Contribute to a traditional IRA

Up to $7,500 for 2026 — as a nondeductible contribution (you don’t take the tax deduction).

2Convert it to a Roth IRA

Ideally soon after, before the money has time to grow much.

3File Form 8606 with your taxes

This documents the nondeductible contribution — it’s what tells the IRS you already paid tax on that money, so the conversion isn’t taxed again.

That’s it. It feels like it shouldn’t be allowed, but it is — this isn’t a gray area or a loophole someone found last week. It’s a well-established, widely used strategy. The work is in doing it cleanly.

⚠ The pro-rata rule is the trap. If you have any existing pre-tax money in traditional, SEP, or SIMPLE IRAs, the IRS treats all your IRA money as one pot. Your conversion gets taxed proportionally across the whole pot — you can’t just convert the “new” after-tax dollars. If you’ve got an old rollover IRA sitting around, talk to a tax professional before you convert. One common fix: roll that pre-tax IRA money into your current 401(k) first, emptying the pot.

The Mega Backdoor Roth: Same Idea, Bigger Door

The regular backdoor moves $7,500 a year. The mega backdoor can move multiples of that — but only if your 401(k) plan cooperates.

Here’s the math. For 2026, the limit on what you can defer into a 401(k) is $24,500. But the limit on what can go into the account in total — your deferrals plus employer match plus a third, lesser-known bucket called after-tax contributions — is $72,000.

Say you max your $24,500 and your employer kicks in $10,000. That leaves up to $37,500 of space that can be filled with after-tax contributions — if your plan allows them. Then you convert those after-tax dollars to Roth, either through an in-plan Roth conversion or a rollover to a Roth IRA, and they grow tax-free from there.

Two boxes your plan has to check:

✓ It allows after-tax (non-Roth) contributions. Not all plans do — check your plan documents or ask your administrator.

✓ It allows in-plan Roth conversions or in-service withdrawals. Without one of these, your after-tax money is stuck earning taxable growth until you leave the job.

Which Door Is Yours?

  Backdoor Roth IRA Mega Backdoor Roth
Who can use it Anyone with earned income Only if your 401(k) plan allows it
Annual ceiling (2026) $7,500 Up to the $72,000 combined limit, minus deferrals and match
Biggest pitfall Pro-rata rule Plan doesn’t support it / forgetting to convert
Paperwork Form 8606 Plan-level conversion or rollover

A note on speed and honesty. Convert promptly — any earnings between contribution and conversion are taxable. And neither of these strategies is “advanced” in the sense of risky; they’re advanced in the sense of paperwork. If your situation has wrinkles (old IRAs, self-employment income, equity comp), this is exactly where a CPA or fee-only advisor earns their fee. I’m sharing the map, not filing your forms.

The Order Still Applies

These doors only matter once you’ve walked the earlier steps — match captured, high-interest debt gone, emergency fund built. If you skipped Part 1, start there. The backdoors are Step 6-and-a-half and Step 7-and-a-half, not shortcuts past the fundamentals.

Ready to figure out how these pieces fit your situation?

Book a Build Better Session →

Enjoy the process. Stay grounded. Scale better.

— Laura

References

  1. Internal Revenue Service (2025). 401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500 — including 2026 Roth IRA income phase-out ranges. Notice 2025-67. irs.gov
  2. Internal Revenue Service. About Form 8606, Nondeductible IRAs. irs.gov
  3. Fidelity (2026). 401(k) contribution limits 2026 — combined employee and employer limit of $72,000. fidelity.com

All views expressed are my own. Nothing shared here is financial, legal, or professional advice... and AI is used ;)