The Backdoor Roth: A Step-by-Step Guide for Earners Above the Limit

You earn $220,000. The Roth IRA phased out for you at $161,000 in 2025 and $165,000 in 2026. You'd like to contribute, but direct Roth contributions aren't allowed at your income level. You've read about the "backdoor Roth" — and every article explains it too abstractly, skips the tax form, or misses the pro-rata rule that causes most backdoor Roth problems.

The backdoor Roth is legal, simple, and widely used. The IRS has known about it since it became workable in 2010 and has made no effort to close it. The mechanics take about 30 minutes once a year. Here's exactly how to do it without triggering the pro-rata rule or messing up your tax filing.

The Legal Basis

There are two separate rules that combine to create the backdoor:

1. Anyone can contribute to a Traditional IRA regardless of income (up to $7,000 in 2026, $8,000 if 50+). If your income is above the deductibility limit, the contribution is non-deductible.
2. Anyone can convert a Traditional IRA to a Roth IRA at any time, regardless of income. The conversion is taxable only on pre-tax amounts.

The backdoor combines these: contribute non-deductible $7,000 to Traditional IRA, then immediately convert to Roth IRA. Since the $7,000 was already after-tax (non-deductible), the conversion is non-taxable. The money is now in a Roth IRA, growing tax-free forever.

The Step-by-Step Execution

At Vanguard, Fidelity, or Schwab, the process is:

1. Open a Traditional IRA if you don't have one (5 minutes online)
2. Open a Roth IRA if you don't have one (5 minutes online)
3. Contribute $7,000 to the Traditional IRA as a non-deductible contribution
4. Wait 1-3 days for the contribution to settle
5. Convert the Traditional IRA balance to the Roth IRA (called "Roth conversion")
6. Invest the Roth balance however you want — VTI, VTSAX, whatever

At Fidelity, steps 4-5 can be completed on the same day. At Vanguard, there's a mandatory 7-day waiting period for new contributions to settle before conversion. Call to confirm timing for your specific brokerage.

The Pro-Rata Rule: The One Thing That Ruins Everything

Here's where backdoor Roths go wrong. The IRS considers all your Traditional IRA assets as a single pool for tax purposes. If you have any pre-tax money in any Traditional IRA at year-end, the conversion is partially taxable.

Example: You have $63,000 in an old rollover IRA from a previous employer (pre-tax). You contribute $7,000 non-deductible this year. When you convert $7,000, the IRS calculates: your total Traditional IRA balance is $70,000, of which $7,000 (10%) is after-tax. So of your $7,000 conversion, $700 is tax-free (after-tax portion) and $6,300 is taxable (pre-tax portion).

You just paid taxes on $6,300 that you didn't intend to convert. The backdoor Roth benefit is mostly destroyed.

How to Avoid the Pro-Rata Problem

Before doing a backdoor Roth, you need zero pre-tax Traditional IRA balance. Your options:

1. Roll your existing Traditional IRA into your current 401(k). 401(k) balances don't count toward the pro-rata calculation. Call your plan administrator and ask about "reverse rollover" — most plans accept them.
2. Convert your entire existing Traditional IRA to Roth in one year. You'll owe tax on the full pre-tax portion, but then future backdoor Roths work cleanly.
3. Don't do backdoor Roths until you've solved this. It's not worth a partial conversion that just creates tax complications.

For most people, rolling pre-tax Traditional IRA balances into a current 401(k) is the cleanest fix. Your 401(k) administrator handles the paperwork; you don't trigger any tax event.

The Timing Question

"How long should I wait between contribution and conversion?"

The "step transaction doctrine" was a concern years ago — the IRS might have combined the contribution and conversion into a single taxable event. But in 2018, Congress explicitly blessed same-day backdoor Roths in the Tax Cuts and Jobs Act conference report. There's no legal reason to wait.

Practical reason: earnings during the waiting period are taxable on conversion. If you contribute $7,000 and wait a week while it earns $15 in money market interest, that $15 is taxable. Converting immediately minimizes this trivial tax cost.

Bottom line: convert as soon as the contribution settles. Same week is fine. Don't make this complicated.

The Tax Filing: Form 8606

The part that scares people the most. IRS Form 8606 is used to track non-deductible IRA contributions and conversions. You file it with your tax return for the year you make the contribution.

On Form 8606, you report:

• Line 1: non-deductible contribution amount ($7,000)
• Line 6: total balance of all Traditional IRAs at year-end (should be $0 if you converted everything)
• Line 8: conversion amount ($7,000 plus any earnings)
• Line 13: non-taxable portion of conversion ($7,000)
• Line 18: taxable portion of conversion (earnings only, probably $0-$30)

If you use TurboTax, H&R Block, or any major tax software, it handles Form 8606 automatically when you enter your 1099-R (from the conversion) and explain the non-deductible contribution. It's not hard — it just requires keeping records of what you did.

Documentation You Need to Keep

Save for each year you do a backdoor Roth:

1. Confirmation of Traditional IRA contribution (date, amount)
2. Confirmation of Roth conversion (date, amount)
3. Copy of filed Form 8606
4. Your 1099-R for the conversion (received from brokerage in January of following year)

The IRS occasionally audits backdoor Roths years after the fact. Having documentation is the difference between a 10-minute response and a several-thousand-dollar headache.

Spousal Backdoor Roth

If your spouse has no earned income, they can still contribute to an IRA via a "spousal IRA" using your earned income. This means a married couple can contribute $14,000 total via backdoor Roth each year ($16,000 if both are 50+).

Rules: each spouse has separate IRAs. Each spouse follows the pro-rata rule independently, based only on their own Traditional IRA balances. Your spouse's $20,000 pre-tax IRA doesn't affect your backdoor Roth.

When to Skip the Backdoor

If your 401(k) has a mega backdoor Roth option (see separate article on that) and you have capacity there, mega backdoor is better than backdoor — higher contribution limits ($46,000 vs. $7,000), simpler mechanics, no pro-rata headache.

If you're already over the Roth phase-out and have pre-tax Traditional IRA balances you can't roll into a 401(k), the backdoor isn't worth the effort. You'll end up paying tax on conversions without getting the backdoor benefit.

The Long-Term Math

$7,000 per year via backdoor Roth, compounded at 7% for 30 years, is $707,000 growing tax-free. That's roughly $250,000 in saved taxes over the lifetime of the account versus having the same money in a taxable brokerage. This is the most lucrative 30 minutes of financial administration you'll do all year.

Do it. Do it correctly. Keep the paperwork. Repeat next year.